How to read it. Each ZIP is colored by the community water system that serves the most of its residents (2020 census block populations against EPA service areas), traced through any wholesale purchases to the utility that actually treats the water. A ZIP is hatched only when more than half of its residents live outside every mapped system, which in Ohio means private wells. Hover for a quick answer; click or search for the full supply chain.
Sources. U.S. EPA Safe Drinking Water Information System (system inventory, intakes, wells, and purchase connections, Ohio EPA primacy data); EPA Community Water System Service Area Boundaries (v3, 2026); U.S. Census TIGERweb ZIP Code Tabulation Areas, counties, and hydrography; USPS place names. Source labels for the largest systems were checked against utility water-quality reports. Boundaries are partly modeled, so edges are approximate.
Violations layer. EPA's Safe Drinking Water Information System compliance record for the community water system that serves most of the ZIP: health-based violations since 2015 (a contaminant above its maximum level, or a treatment technique such as the lead and copper rule not followed), with paperwork violations counted separately and the latest 90th-percentile lead result on the card. A violation is a compliance event, not a measurement of what came out of any one tap, and a large system with one slip counts the same as a village with one; most were resolved. ZIPs on private wells carry no record.
Byproducts layer. When chlorine meets the organic matter in river and reservoir water it forms trihalomethanes and haloacetic acids, the most common contaminants actually measured in Ohio tap water. EPA's Six-Year Review file holds every compliance sample from 2012 through 2019; the map shows the latest yearly mean of total trihalomethanes for the system serving each ZIP against the 80 µg/L annual-average limit, and the card adds haloacetic acids (limit 60), the highest nitrate, arsenic, radium, gross alpha and uranium results, and how many samples sit behind each number. Well systems usually run low; big surface-water systems sit closer to the line, especially in late summer.
Groundwater layer. For the households on private wells, three things from the Ohio Geological Survey: the DRASTIC groundwater vulnerability index of the ground under the ZIP's population center (a 23 to 230 scale built from depth to water, recharge, aquifer, soil, slope, vadose zone and conductivity; higher means contamination from the surface reaches the aquifer more easily, and sand-and-gravel valleys with shallow water score highest), the karst features (sinkholes, springs and closed depressions) the survey has mapped inside the ZIP, where surface water can reach the aquifer in hours, and the state's inventory of water well logs, every well a driller has reported since the 1940s, counted inside the ZIP with median depth, yield and the split between bedrock and sand-and-gravel wells. Vulnerability describes the setting, not measured contamination. The nearest monitoring well adds the measured water table: the latest depth, the 2015 to 2019 average and whether it is running lower or higher. Urban Setting Designation areas, where Ohio EPA has agreed groundwater is not used for drinking, are flagged. Ohio EPA's Class V injection wells inside the ZIP are counted by type. Ohio EPA's wellhead protection areas and sensitive geologic settings, with ODNR's verified sinkholes and springs, say how exposed the aquifer is. A last row names Ohio EPA's nearest ambient groundwater monitoring well, its depth, rock and sampling schedule. A Nitrate risk row gives EPA researchers' modeled chance that a public system in the subwatershed exceeds the nitrate standard, for groundwater and surface-water supplies.
Aquifer layer. Ohio EPA's map of sensitive geologic settings marks the ground where the drinking water aquifer has little natural protection: sand and gravel outwash, buried valleys, karst limestone, or bedrock within a few feet of the surface. The map shows the share of each ZIP in such a setting; the card adds whether the ZIP's center sits on bedrock known to form karst and how much glacial drift covers it (510 of 1,233 centers sit on such rock, 337 on Silurian-Devonian carbonate and 173 on Ordovician limestone and shale, but only 129 under less than 20 ft of drift, where sinkholes are likeliest), ODNR's field-verified sinkholes and springs, and how much of the ZIP lies inside a wellhead protection area or a river intake's emergency zone. It describes exposure, not contamination: a spill, a leaking tank or over-applied manure simply reaches the water table faster there.
Sewage plants layer. Ohio has no statewide map of who is on a sewer, so this layer shows the treatment plants themselves: every publicly owned treatment works of at least 100,000 gallons a day with a Clean Water Act discharge permit in EPA's ECHO database (about 500; the smallest package plants serving a school or a rest area are left out), with its design flow, whether it is a major (over a million gallons a day) plant, whether its system has combined sewer overflows that dump raw sewage in heavy rain, and its compliance record: significant noncompliance status and the number of the last twelve quarters with any violation. The map colors each ZIP by the compliance history of its nearest plant, which is usually the one it drains to. The card also counts combined sewer overflow outfalls within 3 miles from EPA's ECHO inventory: 89 older Ohio sewer systems still have pipes that carry sewage and storm water together and spill the mix into a river when it rains. The card also counts the ZIP's other Clean Water Act permit holders, the factories, water plants and package plants that discharge to streams, with their compliance record. Ohio EPA's own layers add the farm fields permitted for sewage sludge and whether the ZIP sits in a permitted storm sewer area. Ohio EPA's revolving-fund loan history for the ZIP and the nearest permitted sludge generator are added. The section 208 plan's facility planning areas say which agency is allowed to sewer the ZIP. A stormwater line says whether the ZIP sits inside an Ohio EPA regulated MS4 area, where storm sewers carry a permit.
Streams layer. Ohio EPA's 2024 Integrated Report as published in EPA's ATTAINS database: Ohio judges its rivers and streams watershed by watershed (1,545 assessment units) against the uses the Clean Water Act protects. The map shows the share of each ZIP's land in watersheds whose streams fail the aquatic-life standard, the one that says whether fish and insects can live there; the card adds recreation (bacteria), fish consumption and, where a stream is a drinking-water source, that use, plus the listed causes. Nearly every Ohio watershed fails the recreation standard because of bacteria, so aquatic life is the better yardstick. The card also carries Ohio EPA's fish consumption advisories for the rivers and lakes that touch the ZIP: which species to limit to a meal a month or six a year, and whether PCBs or mercury are the reason. The card also carries the USGS estimate of farm pesticide use in the county for 2018, with atrazine, the herbicide most often found in Ohio tap water, called out. Below that sits the county's 2022 Census of Agriculture profile: farms, acres, cropland share, livestock and crop acreage. The nearest Ohio EPA assessment station gives the actual fish, bug and habitat scores behind those verdicts. The nearest station of Ohio EPA's large river PFAS survey gives PFAS in the water and in fish. Ohio EPA's use designations give the miles of exceptional, warmwater, coldwater and modified streams in the ZIP and the nearest superior or outstanding water. Federal critical habitat for endangered mussels and fish is flagged where it crosses the ZIP. Reaches proposed for new antidegradation protection in the 2026 rules are noted.
PFAS layer. Two rounds of testing for the forever chemicals: Ohio EPA sampled every community and non-transient system in 2020 for six PFAS, and EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR 5) sampled every system serving more than 3,300 people, plus a lot of smaller ones, for 29 PFAS and lithium between 2023 and 2025. The map takes the system serving most of each ZIP and colors it by the highest PFOA or PFOS result (at the plant that serves the ZIP, where the system runs more than one) against the 4 nanogram-per-litre limit EPA set in 2024 (compliance is due in 2029, and EPA has proposed an optional two-year extension to 2031 and rescinding its limits on four other PFAS). Trace means other PFAS turned up below the limits; grey ZIPs are on private wells or on small systems that fell outside both rounds. Ohio EPA's own sampling status layer, updated through 2026, adds the latest round for the system, and the county's registered stock of PFAS firefighting foam is noted. The same UCMR 5 round measured lithium, shown on the card against EPA's draft 10 µg/L reference level.
Lead layer. Lead comes from pipes, not from the lake or the aquifer. Every system samples taps in the homes most likely to have lead service lines or lead solder and reports the 90th-percentile result to EPA; the map shows the latest one for the system serving most of each ZIP, against the 15 ppb action level (10 ppb from 2027). The card adds the record since 2016, copper, and the service line inventory every system had to file by October 2024: how many lines are lead, galvanized steel that must be replaced, or still unknown. A Children line says whether the Ohio Department of Health counts the ZIP as high-risk for childhood lead exposure, which makes blood tests at ages 1 and 2 mandatory. Systems that got H2Ohio help building their service line inventory are marked. A housing-age line gives the share of homes built before 1960 and before 1940, the years of lead pipes, solder and paint.
Fluoride layer. Whether the water reaching each ZIP is fluoridated, from the Ohio Department of Health's report to CDC's My Water's Fluoride, with the treatment steps the serving system registers with EPA and, where it buys its water, the steps of the utility that treats it (a buyer such as Gahanna registers no treatment of its own because Columbus fluoridates the water before selling it), with the whole treatment train on the card: chlorination or chloramine, softening, iron removal, activated carbon, membranes. Ohio has required fluoridation of systems serving 5,000 or more people since a 1969 law, unless the community exempted itself by ordinance or vote in the window the law allowed, which is why a handful of cities sit unfluoridated among fluoridated neighbors; smaller systems and naturally fluoridated wells decide for themselves. EPA's 2012 to 2019 compliance samples give the fluoride actually measured leaving the plant. Blue is fluoridated, teal natural fluoride at the dental level with no fluoridation step, gold not fluoridated.
Algal toxins layer. Since the August 2014 weekend when Toledo told half a million people not to drink the tap water, Ohio EPA has had every surface-water system test its raw and treated water for microcystin through the bloom season. The map shows the highest raw-water reading since 2016 at the intake of the system serving most of each ZIP, which is what the plant has had to remove; the card adds any detections in treated water against the 0.3 and 1.6 microgram-per-litre advisory levels, and the seasons in which the bloom reached the intake. Groundwater systems are not monitored and stay grey. Grand Lake St. Marys, the state's most bloom-prone lake, gives Celina the worst raw-water readings in Ohio, and the western Lake Erie intakes at Toledo, Oregon and Ottawa County see the summer bloom most years.
Watershed layer. Every drop of rain that falls in Ohio ends up in Lake Erie or the Ohio River, and the divide runs across the state's middle. This layer uses the USGS Watershed Boundary Dataset: each ZIP takes the 8-digit subbasin where most of its residents live (44 touch Ohio, from the Maumee to the Little Scioto), colored blue for the Lake Erie side and purple for the Ohio River side with shades separating neighbors, and the card names the small 12-digit subwatershed under the ZIP's population center and the creeks and rivers the water passes through on its way out. Watersheds, not city limits, are how Ohio EPA assesses streams and how a spill upstream reaches a water intake. The card ends with the county's water budget from the USGS 2015 water-use census: how much is pumped each day, how much of it goes to public supply, power plants, industry and irrigation, and how many residents draw their own wells. The card also lists nearby H2Ohio water-quality projects and, along Lake Erie, whether the ZIP falls in the Coastal Management Area. Approved nine-element nonpoint source plans (and the acid mine drainage and EPA Region 5 plans Ohio EPA lists with them) are noted for the subwatershed at the ZIP's center. H2Ohio road-salt grants near the ZIP are listed. Ohio EPA's surface water protection areas show which downstream intakes the ZIP drains to and whether it sits in an emergency zone. Section 319, GLRI and SWIF runoff projects near the ZIP are listed. NOAA's Lake Erie gauges give the current lake level against the 1991 to 2020 average for coastal ZIPs. An EnviroAtlas line gives the subwatershed's Conservation Reserve acres, grain cropland, stream miles, water use, precipitation and nitrogen deposition from EPA's national metrics. A stream-permits line reads Ohio EPA's 401 certification map: whether stream work in the ZIP can use the Army Corps' blanket nationwide permits or needs an individual review because the water drains to high-quality streams.
Radon layer. Ohio Department of Health, radon levels by ZIP code: every test reported by Ohio-licensed radon professionals since 2010, before any mitigation, updated monthly. The map shows the ZIP's average; ZIPs with fewer than five tests are left grey. Some ZIP codes in ODH's list have no Census ZIP area to draw (mostly post-office-box or single-address codes, it appears), so their tests, about 0.4% of the total, are counted in the statewide figure but not shown on the map. A ZIP average says nothing about one house, and EPA's advice is the same everywhere: test, and fix at 4 pCi/L or more.
Electric layer. Outage figures are the utility's 2024 report to the Energy Information Administration (Form 861), or 2023 where the utility did not file: SAIDI, the minutes the average customer was without power over the year, with and without the major storm days utilities are allowed to set aside, and SAIFI, the number of sustained interruptions per customer. Ohio's rural co-ops and the FirstEnergy companies report the longest outages; small municipal systems the shortest. PUCO certified electric territories (investor-owned utilities and cooperatives, annual, via ODOT) and the municipal electric systems from the federal HIFLD retail service territory inventory (EIA Form 861), each drawn with its corporate limits. A ZIP takes the utility that delivers power to the most of its residents, by the same census-block method as the water layer. Cleveland Public Power and Columbus Division of Power serve parts of their cities alongside the investor-owned utility and are noted rather than colored. The same EIA filing gives each utility's net-metered solar customers and its share of smart meters. An energy-burden note gives the share of income households spend on electricity, gas and other fuels, from the Department of Energy's LEAD Tool, with the figure for lower-income households and the share of households above the 6 percent line.
Power plants layer. Every generating plant in the Energy Information Administration's Form 860 inventory: the nearest plant of 100 megawatts or more, the plants within 10 miles by fuel, the nearest wind farm and utility-scale solar farm from the USGS databases, and, for ZIPs within 50 miles of the Perry or Davis-Besse nuclear plants, which emergency planning zone they fall in.
Gas layer. Ohio publishes no gas territory boundaries, so this layer combines three sources: PUCO's April 2026 map of the gas distribution companies operating in each county (from its pipeline-safety database), the federal HIFLD territory polygons (EIA Form 176, 2016 vintage, the newest public boundaries), and the Census Bureau's count of how homes heat (ACS 2020 to 2024). A ZIP takes the company whose territory covers the most residents among the companies PUCO lists for that county; municipal limits win, then the four large utilities, then small companies and cooperatives, whose polygons cover far more ground than their mains. A ZIP where under a fifth of homes heat with utility gas is drawn faded.
Schools and phone layers. Public school district boundaries from the state's OGRIP layer (2014 edition, via ODOT), colored by district type with shades separating neighbors; a ZIP takes the district where most of its residents live, and the card shows the split. Incumbent local telephone company territories from PUCO, the exchange areas the legacy landline carrier holds; cable, fiber and wireless providers compete inside them and are not mapped.
School ratings layer. Ohio's 2024-2025 School Report Cards give every district one to five stars overall, built from six components: achievement (the performance index on state tests), progress (value-added growth), gap closing, early literacy, graduation and college-career-workforce-military readiness. The map shows the overall stars of the district holding the largest share of each ZIP's residents (in 46 ZIPs that district holds under half of them, and the card names the others), and the Schools card adds each named school building's own stars; the card lists the components, the performance index, four- and five-year graduation rates, spending per pupil against the state figure and the teaching staff's pay, experience and credentials. Three stars means the district meets state standards, five that it significantly exceeds them and one that it needs significant support. Star ratings track family income closely, so a low rating says more about who a district serves than how well it teaches. NCES's private school survey adds the private schools inside the ZIP and their enrollment. The district card also carries the Census Bureau's school finance survey for fiscal 2023: revenue and where it came from, spending per pupil and the share going to instruction. The Census Bureau's 2024 small-area estimate of school-age children in poverty follows. Enrollment at the public schools inside the ZIP, the charter schools among them, students per teacher and the share qualifying for free or reduced-price meals come from the federal Common Core of Data; online schools are listed separately because their address is an office.
School tax layer. The Ohio Department of Taxation's aggregate property tax rates by school district for tax year 2025: the effective Class I (residential and agricultural) millage each district collects after the reduction factors that hold voted levies to the dollars first approved, weighted across the districts a ZIP's residents live in. School levies are usually the largest share of an Ohio property tax bill but not all of it; county, city or township, library, park and vocational-school millage are collected in the same bill and are not in this table, and the 10 percent and owner-occupancy credits, homestead exemption and any new levies since 2025 change what a household pays. The card now also lists the municipal income tax, school district income tax and combined sales tax rate for the ZIP from the Department of Taxation's Finder tables.
Flood, internet and hazard layers. Flood: FEMA's National Flood Hazard Layer, the effective flood insurance rate maps, downloaded county by county; a ZIP is scored by the share of its residents whose 2020 census block center falls inside the 1% annual chance floodplain, with the land share and the 0.2% zone on the card. Internet: the FCC's Broadband Data Collection for June 2024, summed from hexagons to ZIPs, giving the share of homes and businesses that can get 100/20 Mbps fixed service and the reach of fiber and cable, beside the Census count of households that actually subscribe. Hazards: FEMA's National Risk Index, which scores every census tract against the nation on 18 natural hazards, weighted here to ZIPs by block population.
Climate layer. NOAA's 1991-2020 climate normals, the thirty-year averages weather forecasters mean by "normal": annual snowfall on the map, with mean temperature, January lows and July highs, days at 90°F or above and below freezing, rainfall, and heating and cooling degree days on the card. Ohio has 130 stations with temperature normals, 252 with precipitation and only 93 with snowfall, so each ZIP borrows from the nearest station reporting each element and names it. The Lake Erie snowbelt east of Cleveland gets four to five times the snow of the Ohio River counties. The card also carries the county's drought history from the U.S. Drought Monitor: weeks in drought since 2020, the worst spell since 2000 and the current status. NOAA's county series since 1895 gives the long-run warming and the change in yearly rainfall.
Dams, transit and airports layers. Dams from the Army Corps of Engineers' National Inventory of Dams: "high hazard" is the consequence if a dam failed (people downstream would probably die), not its state of repair; the condition assessment on the card is the separate inspection verdict, and Ohio rates more than a third of its dams poor. Transit stops are the GTFS feeds every agency reporting to the National Transit Database publishes, as gathered by the National Transit Map, plus five Ohio systems' feeds taken from the agencies themselves (Springfield, Lancaster-Fairfield, Knox County Transit, WayGo in Wooster and the BGSU Shuttle); a ZIP is scored by the share of residents whose census block center is within half a mile of any stop, and dial-a-ride services, along with the few fixed-route systems that publish no feed at all, are missing. Airports are FAA facilities with scheduled airline service under Part 139, including the out-of-state airports that serve Ohio's edges, with the nearest public-use airfield and Amtrak station on the card.
Health and historic layers. Health: CDC's PLACES project (2025 release) estimates adult health for every ZIP Code Tabulation Area by combining the Behavioral Risk Factor Surveillance System survey with Census demographics; the numbers are modeled, not counted, and carry wide margins in small ZIPs. The map shows the share of adults who call their health fair or poor; obesity, diabetes, smoking, depression, insurance and food insecurity are on the card. Historic: every National Register of Historic Places listing that has a point in the National Park Service's file (about three quarters of Ohio's listings), counted inside each ZIP; a district counts once at its center point.
History layer. Colors each ZIP by the year the place most of its residents live in was first settled or platted, and the History card tells that place's story: the Native nations and sites recorded there and in its county, how the town began and got its name, a dated timeline, stories, photographs and the county's own history, with a statewide note on Ohio's peoples, earthworks and treaties. The research runs county by county outward from Franklin County; Sonnet and Opus research agents write one file per municipality and township from Wikipedia, the 1880s county histories on archive.org, Ohio History Connection, National Register listings, Ohio historical markers and local historical societies, and every claim carries the page it came from. Photographs are public domain or Creative Commons, each with its credit and license. The files load on demand, so the card takes a moment the first time a county is opened.
Disasters layer. Three records of what has actually happened: every tornado track in the Storm Prediction Center's database since 1950 that passes within 5 miles of the ZIP's population center (a track is the straight line from touchdown to lift-off, so a tornado that lifted a mile away counts), every federal disaster or emergency declaration FEMA has issued for the ZIP's county, from Ohio's first in 1956, including statewide ones, and every earthquake of magnitude 2 or more the USGS has cataloged within 25 miles since 1970. Tornado ratings are the Fujita scale before 2007 and the Enhanced Fujita scale after. The card also totals NOAA's Storm Events log for the county since 2016: hail, damaging wind, flash floods, lightning and the rest, with the largest hail, the strongest measured gust and the costliest single event. A county line tallies every tornado, severe thunderstorm, flood, winter storm and heat warning the National Weather Service has issued since 2015. FEMA's mitigation grant history for the county and the properties bought out, elevated or given safe rooms in the ZIP are listed. FEMA's household registrations after each declared disaster show who actually applied for help.
Jobs layer. The Census Bureau's LEHD Origin-Destination Employment Statistics for 2023, built from state unemployment-insurance records: every job is tied to a workplace block and a home block. The map shows jobs located in the ZIP per employed resident, so a downtown or an industrial park reads high and a bedroom suburb low; the card lists the largest industries, the share of jobs paying over $3,333 a month, and where the ZIP's residents actually work. The self-employed, the military, the Postal Service and most farm work are not covered, and federal civilian jobs, added from OPM records, are only partly counted. ZIP Business Patterns adds the count of business establishments, their employees and payroll, and the most common sectors. OSHA's enforcement records add the workplace inspections in the ZIP since 2020, what triggered them, and the worker deaths and hospitalizations its investigators looked into since 2015. A county line gives the BLS unemployment rate for the latest month and the average weekly wage and largest private sectors from the Quarterly Census of Employment and Wages. USDA's county typology says whether the county leans on manufacturing, government or mining and which distress flags it carries. Opportunity Zone tracts are noted. Labor force participation and the unemployment rate of residents 16 and over come from the Census American Community Survey, averaged over 2020 to 2024. Residents' most common occupations and the self-employed and government shares are Census survey figures.
Upward mobility layer. The Opportunity Atlas followed twenty million Americans born between 1978 and 1983 from the neighborhood they grew up in to their tax returns in their mid-thirties. For each census tract it reports the average income rank reached by children whose parents were at the 25th percentile, roughly a household making $27,000 in today's money. The map shows that rank, population-weighted to each ZIP: 50 means those children reached the national middle, 30 that they stayed near the bottom. The card adds the share of those children who were in jail or prison on census day 2010. Outcomes are for the people who grew up there thirty years ago, not for today's children, and tracts that split since 2010 are left out.
Vulnerability layer. The CDC's Social Vulnerability Index scores every census tract on sixteen Census measures of how hard a disaster or an outbreak would hit its people: poverty, unemployment, housing cost burden, education and health insurance; age, disability and single-parent households; language and minority status; and crowded housing, mobile homes, group quarters and households without a vehicle. The map shows each ZIP's population-weighted percentile among Ohio tracts, from the least vulnerable fifth to the most; the card breaks the score into its four themes. Emergency planners use it to decide where to send help first; it says nothing about the water.
Crime layer. The FBI's National Incident-Based Reporting System collects every offense Ohio police agencies record. The map shows violent offenses (murder, rape, robbery and aggravated assault) per 1,000 residents in 2024 for the police department of each ZIP's largest local government (city, village or township), or the county sheriff where that government has no police of its own; a ZIP whose department sent the FBI less than six months of 2024 stays grey. The card adds property crime, drugs, weapons and vandalism, how many months the agency reported, and the statewide rates for comparison. A rate belongs to the whole agency's territory, so a big city's number covers its calm neighborhoods and its rough ones alike.
People layer. Census American Community Survey five-year estimates by ZIP Code Tabulation Area: the share of adults 25 and over with a bachelor's degree or higher on the map, with graduate degrees, high school or less, race and Hispanic origin, the foreign-born share and veterans on the card. Five-year survey averages centered on 2022; small ZIPs carry wide margins of error. The card ends with the county's migration from IRS address changes: how many people moved in and out between returns filed in 2022 and 2023 (tax years 2021 and 2022) and where they came from and went. The county growth row gives the Census Bureau's 2025 estimate against the 2020 count, with births, deaths and migration. A second row traces the county's population back to 1900 through the decennial censuses and names its peak. Two more rows give the county's USDA rural-urban classification and the tax-exempt organizations registered in the ZIP. USDA's rural-urban commuting area code says whether the ZIP is a metro core, a commuter suburb, a small town or open country. The 2020 Census count of people living in group quarters (college housing, nursing facilities, prisons and jails, shelters) is summed from blocks to the ZIP. Household size, people living alone, married couples, poverty by age and the Gini index come from the same survey. The most often reported ancestries, who moved in the past year and households with limited English come from the same survey. The largest countries of birth among the foreign-born come from the same survey. The poverty row closes with the county's 2024 small-area estimate and median household income. A household-mix row gives homes with children, homes with seniors, seniors living alone and marital status.
Oil and gas wells, mines and power plants. Wells from the Ohio Department of Natural Resources' public inventory of the 242,000 wells in its database (records before permitting began are incomplete, and estimates of wells ever drilled in Ohio run to 275,000): the map counts wells inside the ZIP, the card splits them into producing, plugged, horizontal shale (Utica and Marcellus), injection and orphan-program wells, and names the largest active operators. Mines are ODNR's maps of underground coal and mineral mines abandoned before 1977, the ones that can subside or leak acid water; the map shows the share of a ZIP's land above one, and "partly mapped" means the extent is inferred. Power plants come from the Energy Information Administration's plant inventory (EIA-860) as published by HIFLD: the map shows the distance to the nearest plant of 100 megawatts or more, with everything within 10 miles by fuel on the card. Solar farms now outnumber every other kind in Ohio.
Soils layer. The USDA soil survey (SSURGO) map unit under each ZIP's population-weighted center, fetched from Soil Data Access: its dominant soil, drainage class, whether it is hydric (wet enough to have formed under water), farmland class, flooding and ponding frequency, and two engineering ratings that decide what a rural lot can do: Ohio's own rating for septic leach fields and the national rating for houses with basements. A single point stands for the whole ZIP, so treat it as the typical soil, not the soil under any one lot; Ohio's clay till plains rate "very limited" for septic almost everywhere, which is why county health departments require engineered systems. The card ends with the elevation of the ZIP's population center from the Copernicus global elevation model.
Life expectancy layer. The CDC's small-area life expectancy project estimated life expectancy at birth for every census tract from deaths in 2010 to 2015 and the 2010 census; the map weights the 2010 tracts into each ZIP by its 2020 block population and the card shows the spread across the ZIP's tracts. It is the average number of years a newborn would live if the tract's death rates of that period held for life, so a poor inner-city ZIP and a wealthy suburb ten miles apart can differ by fifteen years. The estimates are a decade old and carry standard errors of one to two years in small tracts.
Health layer. CDC PLACES model-based estimates of adult health for every ZIP: self-rated health, obesity, diabetes, smoking, depression, insurance, disability and more. The county paragraph adds County Health Rankings 2025, which places every U.S. county in a health group and reports premature death, access to doctors, dentists and mental health providers, preventable hospital stays, injury, suicide and infant deaths, teen births, child poverty, air quality and whether a water system in the county had a health-based violation, plus the CDC's provisional count of drug overdose deaths for the latest 12 months. NCI State Cancer Profiles add the county's cancer incidence and death rates against Ohio and the nation. Further PLACES measures cover asthma, heart disease, stroke, arthritis, blood pressure control and the social needs the survey now asks about. Census survey rows give the uninsured, Medicaid and employer-coverage shares and the share of residents with a disability. A county line gives Medicare enrollment, the Medicare Advantage share and dual Medicaid enrollment from CMS. The Nearest hospital card counts the physicians, dentists, pharmacies, mental health professionals and facilities registered to practice addresses in the ZIP (NPPES).
Pipelines layer. The Energy Information Administration's map of natural gas transmission pipelines, the large interstate and intrastate lines that move gas between states and to city gates, republished on ArcGIS Online by Esri's Federal User Community. The map shows the distance from each ZIP's population center to the nearest operating line; the card gives the miles of transmission pipe inside the ZIP by operator. Local distribution mains under the streets, gathering lines from wells and liquids pipelines are not included, and the federal map is generalized, so a line can be a few hundred yards off.
Rail crossings layer. The Federal Railroad Administration's crossing inventory, the record every railroad and state must keep of each place a road, path or station platform crosses a track: the map counts the open public at-grade crossings inside each ZIP, and the card gives the railroads, how many have gates, the trains a day reported at the busiest crossing, the fastest timetable speed, and the private crossings. Train counts are what the railroad last reported and can be years old; a crossing with 80 trains a day on a 79 mph main line is a different neighbor from a switching spur. FRA incident reports count the collisions at the ZIP's crossings since 2010. FRA accident reports add derailments and hazmat releases in the ZIP and county since 2010.
Wetlands layer. The U.S. Fish and Wildlife Service's National Wetlands Inventory for Ohio, mapped from aerial photographs: freshwater marshes (emergent), swamps (forested and shrub) and ponds, clipped to each ZIP, with open lakes and river channels left out. Ohio drained about 90 percent of its original wetlands, so what remains is concentrated in the northwest's Great Black Swamp remnants, the Lake Erie marshes and the glacial kettles of the northeast. Mapped wetlands carry federal and state permit requirements for filling, and they are where the water table sits at the surface. Ohio EPA's vernal pool screening, high-quality wetland list and mitigation sites are noted. Ohio EPA's own wetland assessments add the nearest studied wetland with its ORAM and plant community scores. Where USGS topographic maps marked marsh or swamp, the card gives those acres too.
Land cover layer. The National Land Cover Database classifies every 30 meter pixel of the country from Landsat imagery: four intensities of developed land, forest, cropland, pasture, grass and shrub, water, wetland and barren ground, with companion layers for percent impervious surface and tree canopy. The map shows the developed share of each ZIP's land; the card gives the full breakdown, the impervious share (roofs and pavement that shed rain straight into storm drains and streams) and the tree canopy. The USDA Cropland Data Layer splits the cropland into corn, soybeans, wheat and hay. A last row reaches back before settlement: what the original land surveys of the early 1800s recorded on the same ground, from ODNR's mapping of the surveyors' notes, including how much was swamp, marsh or prairie.
Walkability layer. The EPA's National Walkability Index scores every census block group from 1 to 20 on three things that make walking practical: intersection density, distance to the nearest transit stop, and how mixed the jobs and homes are. The map shows each ZIP's population-weighted score in the EPA's four bands, from least walkable to most; the card breaks out the parts and adds the share of households with no car.
Traffic layer. ODOT publishes annual average daily traffic, the number of vehicles passing a point on an ordinary day, for its state, US and interstate routes and for about 46,000 miles of county, township and city roads. That is 68,000 miles in all, a little over half of Ohio's 123,000 miles of public road, so most city streets have no count at all. The map shows the busiest counted segment inside each ZIP, from a few hundred vehicles on a township road to about 195,000 on I-270 in Franklin County; the card adds the trucks on it, the total vehicle-miles driven inside the ZIP each day, the busiest counted county, township or city road, and how many segments carry freeway volumes. Counts are the 2025 set from ODOT's Transportation Information Mapping System. The card closes with the fatal crashes NHTSA recorded inside the ZIP from 2020 to 2024: deaths, pedestrians and cyclists, drinking drivers, and the road carrying the most where one road stands out.
Bridges layer. The Federal Highway Administration's National Bridge Inventory for 2025, every public road bridge and large culvert in Ohio with its inspection ratings: the map shows the share of a ZIP's bridges rated poor (a deck, superstructure, substructure or culvert scored 4 or lower on the 0 to 9 scale), and the card gives the count, the typical and oldest build years, the busiest bridge by traffic and the poor-rated ones by name. Poor does not mean unsafe to cross; it means repair or replacement is due, and a bridge judged unsafe is closed or load-posted. ZIPs with fewer than three bridges are left grey because one bridge would swing the share.
Local government layer. ODOT's municipal corporation and township boundaries; a city or village takes precedence over the township it lies in, and a ZIP takes the government where most of its residents live. Townships are the unincorporated remainder, governed by elected trustees. Ohio EPA grants to local bodies and the Auditor of State's unauditable list are noted.
Cell signal layer. The FCC's Mobile Broadband Data Collection: AT&T, T-Mobile and Verizon report where their 4G LTE and 5G networks reach outdoors at a stationary spot, on a grid of hexagons about a tenth of a square kilometer each. A ZIP is scored by the share of its land with 5G from any of the three; the card gives each carrier. Coverage is the carriers' own claim, by area rather than by people. The card also counts the antenna structures registered with the FCC inside the ZIP and within 3 miles, with the tallest. Ookla's crowd-sourced speed tests give the measured mobile download, upload and latency for the ZIP.
Representatives and hospital layers. U.S. House, Ohio Senate and Ohio House district boundaries from ODOT, with members from the chambers' own directories; a ZIP cut by a district line shows every member who serves part of it. Hospitals from the federal HIFLD inventory: the distance is a straight line from the ZIP's population-weighted center to the nearest open general or critical-access hospital, and the inventory can lag closures and mergers.
Spills layer. Ohio EPA's emergency response office logs every reported release, from diesel out of a wrecked truck and transformer oil off a pole to brine from a well pad and sewage from a broken main, most of them with a location. The map counts the reports inside each ZIP since 2021, about 2,400 a year statewide; the card sorts them by what spilled, names the largest reported in gallons, barrels, drums or quarts and says how many reached a creek, ditch or storm drain (about one in six). Interstates, rail yards, refineries and the shale counties dominate, and many reports turn out to be a sheen or a few gallons, so the count measures activity and traffic as much as hazard.
Toxic sites layer. EPA's Facility Registry Service: Superfund National Priorities List sites (on, proposed, or deleted after cleanup), the wider Superfund program list of sites ever assessed, and facilities that have reported to the Toxics Release Inventory. A ZIP is colored by whether an NPL site lies inside it, otherwise by the distance to the nearest one, including sites just across the state line in Pennsylvania, West Virginia, Kentucky, Indiana and Michigan. Reporting to the inventory records chemical use and release, not a measured exposure. Ohio EPA's Voluntary Action Program covenants mark former industrial sites certified clean. Ohio EPA's licensed landfills, transfer stations and compost sites round out the picture. ECHO's hazardous waste handler list adds violations, penalties and the nearest treatment, storage or disposal facility. The card ends with the nearest scrap tire and household battery drop-off sites from Ohio EPA's lists. EPA's UST Finder adds the gas-station-style underground storage tanks inside the ZIP and the leaking-tank releases reported there, with those inside a drinking-water source protection area called out.
Toxic releases layer. The Toxics Release Inventory is the yearly report that factories, power plants, mines and other facilities in listed industries must file when they handle more than a threshold of any of about 800 listed chemicals: how many pounds went to the air, to surface water, to land or down an injection well, and how much was shipped elsewhere. The map shows the pounds released on site in 2024 inside each ZIP; the card breaks them out by medium, names the chemicals and facilities, flags carcinogens and PFAS, lists direct discharges to water, and compares with 2020.
Home prices layer. The Federal Housing Finance Agency's house price index follows the same houses through repeat sales and refinance appraisals on conforming mortgages, ZIP by ZIP, back to the 1980s in most of Ohio; FHFA calls the ZIP series developmental. The map shows the change over the latest ten years of each ZIP's index (2015 to 2025 for most), and the card adds the five-year and one-year changes and how far prices stand above their 2000 level. The median Ohio ZIP gained 92% in the decade, against inflation of roughly a third; inner-city Columbus and Cincinnati neighborhoods more than tripled, a few small-town ZIPs barely moved, and rural ZIPs with too few sales have no index at all. Realtor.com's monthly listing metrics and Zillow's rent index show what the market is asking right now.
Building permits layer. The Census Bureau's Building Permits Survey collects, from every permit office in Ohio, the new privately owned housing units it authorized each year: single-family houses, duplexes, small buildings and apartment buildings of five or more units, with the construction value the applicant declared. The map shows units authorized from 2016 through 2025 per 1,000 residents of the city, village, township or county building department that covers most of each ZIP, and the card gives the yearly counts, the mix and the dollar value. Columbus alone permitted 52,000 units in the decade, most of them apartments; the county building departments of Union, Delaware and Warren counties lead per head. Remodels and commercial work are not in the survey, and in the 39 counties whose county office reports only buildings of four or more units, houses in the townships are not counted at all. For Columbus and Westerville the card can list every permit on every house in the ZIP since 2016, loaded only when asked for: house numbers, dates, the work, the declared value and the contractor, from the cities' own permit records.
Homes layer. Census American Community Survey five-year estimates by ZIP Code Tabulation Area: median owner-estimated home value on the map, with median gross rent, median household income, owner-occupied share, and the median year homes were built on the card. The card also gives the Eviction Lab's estimate of eviction filings per 100 renter households for 2016 to 2018, the last years its tract series covers. HUD's fair market rent for the ZIP and the IRS's summary of its 2022 tax returns, average income and the shares at the top and bottom, complete the card. Where the Home Owners' Loan Corporation drew its 1930s security maps, the card gives the share of the ZIP's area in each grade, D being the redlined hazardous zones. HUD's property files add the public housing, tax-credit and HUD-assisted apartments inside the ZIP, and the FDIC's branch list the bank branches or the distance to the nearest one. Vacancy (for rent, for sale, seasonal, other) and the share of owners spending 30 percent or more of income on housing come from the same survey. The card also gives the income spread, the share of owners with a mortgage and crowding. Rows for the spread of home values, income per person, when owners and renters moved in, the median rent and mortgage cost burdens and long commutes come from the same survey.
Houses layer. House by house, from county parcel records, starting in central Ohio and working outward from Franklin County. Where a county auditor's own appraisal records are in, the map colors each ZIP by the median year its homes were built, and the card gives the homes by kind, their age (with the share built before 1978, the year lead paint was banned for housing), median living area, lot and appraised value, sales over the last year and five years, owner-occupancy and company ownership, then the ZIP's neighborhoods and subdivisions with their own medians and every house with its record: year built, living area, rooms, construction, appraised value and tax, sales since 1990, the building permits on file for its address and a link to its page at the county auditor. In counties whose appraisal records are not in yet, the ZIPs stay grey and carry only the parcel list from OGRIP's Ohio Statewide Parcels (address, land-use class, lot size and the auditor's parcel link, in county uploads of varying age). Zoomed in on a selected ZIP whose houses are loaded, each house draws as a dot colored by year built, following the card's search and filters. Appraised values are the auditor's market value for property tax, not sale prices; sale medians count single-parcel sales of homes, one per house, and only the sales the auditor marks valid where the county marks them (otherwise every sale of $10,000 or more). Neighborhoods are the boundaries cities publish (official neighborhoods first, then planning areas and civic associations); subdivisions are the auditor's plat names. Owner names, mailing addresses and exemptions that reveal a person's circumstances are never carried; an owner is described only as a person or family, a company, a government body, or a church or nonprofit.
Air layer. EPA's Air Quality System annual summaries for 2025: the map shows the annual average of fine particulate matter (PM2.5) at the monitor nearest each ZIP's population-weighted center, against the 9 µg/m³ national standard adopted in 2024. Ohio has only 38 PM2.5 monitors, so a reading can come from a city 30 miles away; the card gives the distance, the nearest ozone monitor's fourth-highest daily reading (the design-value ingredient, 70 ppb standard), and the county's Air Quality Index day counts where the county has a monitor of its own. EPA's ECHO adds the permitted air sources inside the ZIP, their classification and their recent violations. EPA's Green Book says whether the county is in nonattainment or under a maintenance plan for any standard. A second county row counts the good, moderate and worse days indexed so far in 2026, as far as EPA's daily file runs.
Fire/EMS and library layers. Fire and EMS stations from the USGS National Map structures inventory (1,772 Ohio stations after removing three duplicate records and checking Columbus- and Cleveland-area stations against the cities' own station lists, plus the Indiana, Michigan and Pennsylvania stations near the state line); public library buildings from the Institute of Museum and Library Services' Public Libraries Survey for fiscal 2024 (central libraries and branches, bookmobile stops and outreach units excluded), with each system's hours, visits and budget. Both use straight-line miles from the ZIP's population-weighted center, so a station across a river may be nearer by air than by road.
Groceries layer. USDA's Food Access Research Atlas 2019 Large Retailer Access Map (ERS's name for the file since July 2026; on 2010 census tracts, using a 2019 supermarket list). A tract is flagged low-income and low-access when its poverty rate is high or incomes low and a large share of residents live more than 1 mile from a supermarket in an urban area or 10 miles in a rural one; the map shows the share of a ZIP's residents in flagged tracts, weighted by 2020 census block population. Distance shares are on the card. Dollar stores and small groceries do not count as supermarkets. USDA's current SNAP retailer list counts the supermarkets, grocers and convenience stores inside the ZIP and finds the nearest supermarket, superstore or grocery store, including stores just across the state line. The shares of households without a vehicle and of households that received SNAP in the past year come from the Census survey.
EV chargers layer. The National Renewable Energy Laboratory's Alternative Fuels Data Center station list, through the Department of Transportation's copy (station list as of May 29, 2026): public, open electric stations only (private fleet, workplace-only, planned and NREL restricted-access sites, such as dealer-service and hotel-guest chargers, dropped). NREL lists every post at a site as its own record, so the posts of one network at one address are merged into a single site before anything is counted. The map shows the straight-line distance from the ZIP's population-weighted center to the nearest public DC fast charger, counting chargers across the state line in Pennsylvania, West Virginia, Kentucky, Indiana and Michigan as well; the card counts the Ohio stations and Level 2 and DC fast ports inside the ZIP, the stations within 5 miles of that center, and the networks. Tesla Superchargers open to other makes appear as they are listed by NREL.
Parks layer. The USGS Protected Areas Database (PAD-US 4.1, Ohio package): every park, forest, wildlife area, reservoir recreation area and preserve whose owner reports open public access, from city parks to Wayne National Forest, with proclamation boundaries, closed easements, farmland easements and military land left out. The map shows the share of each ZIP's land inside those areas; the card lists the largest units by acres inside the ZIP and the straight-line distance to the nearest state park run by the Department of Natural Resources. PAD-US inherits local inventories of uneven quality, so a golf course or a school field can appear as a park and a new metropark can be missing. ODNR's facility layers add the nearest boat ramp, fishing access, swim area and campground on state lands. ODNR's statewide trails inventory lists the named trails and state bike routes crossing the ZIP. The USGS Protected Areas Database gives the share of the ZIP that is public or permanently protected land, by manager.
Nursing homes, police and colleges layers. Nursing homes from Medicare's Care Compare provider file (every Medicare- or Medicaid-certified home, with its overall, health-inspection and staffing star ratings), geocoded with the Census Bureau's address geocoder; the 67 addresses it could not place sit at their ZIP's center and are marked approximate. Police stations and post offices from the USGS National Map structures inventory; colleges from the NCES IPEDS 2024 directory, with enrollment, tuition and graduation rates from the IPEDS survey files and closed institutions dropped. All three use straight-line miles from the ZIP's population-weighted center.
Infrastructure overlays. The Infrastructure button on the map draws real geometry over any layer: natural gas transmission pipelines and crude, product and natural-gas-liquid lines (EIA, via Esri Federal User Community copies on ArcGIS Online), compressor and storage sites, refineries and terminals, electric transmission lines and substations (HIFLD), power plants (EIA-860), wind turbines and solar farms (USGS); large water mains and interceptor sewers where a city or county publishes its utility GIS, sewage plants (EPA ECHO), combined sewer overflows, dams (National Inventory of Dams), levees (FEMA), locks, ports and shipping lanes (Army Corps, BTS); Interstate, US and state routes with traffic counts (ODOT), major bridges (National Bridge Inventory), every railroad line, yard and crossing (BTS rail network, FRA), Amtrak, airports and runways (FAA), transit routes and stations (BTS National Transit Map), ferries; cell towers (FCC), EV chargers (NREL), landfills and waste facilities (Ohio EPA), brine injection and gas storage wells (ODNR), Superfund sites, pipeline incidents (PHMSA), USGS stream gauges, hospitals, fire and police stations, post offices. Gas and water distribution pipes under streets are not public data anywhere in Ohio; the gas company card carries PHMSA's mileage and material figures instead. Dense layers draw as you zoom in; hover anything for what it is and click for its card and source.
Base map. The Atlas, Streets and Satellite buttons at the bottom of the map switch what lies under the ZIP colors: the atlas's own drawing, a street map that shows every mapped building footprint once you zoom in (OpenStreetMap), or satellite and aerial imagery (Esri World Imagery, from Vantor, Earthstar Geographics and other providers). Under a street or satellite base the map redraws in Web Mercator so the tiles line up, the ZIP colors turn translucent so the ground shows through, and the atlas's own rivers and lakes stay off because the base draws them; every overlay, marker and card works as before, and the map zooms in far enough to see single roofs. Tiles come from the OpenStreetMap and Esri servers as you pan, so they need the internet and take a moment to arrive. On the published page, whose host blocks images from outside servers, the satellite base instead draws USDA and USGS aerial imagery bundled with the atlas (The National Map cache refreshed June 2024; the NAIP photographs are 2017 to 2021), sharp to about county level and enlarged beyond that, with the atlas's own lakes kept on because that imagery leaves open Lake Erie blank, and the street base is not available.
Every layer, its source, and how many ZIP codes it covers. Generated from the data file at build time.