Ohio County area

Ohio County, Kentucky covers 596.2 square miles: 587.1 square miles of land and 9.132 square miles of water. Its county seat is Hartford. An estimated 23,934 people lived there in 2025.

Official Census measurements · GEOID 211832026 Gazetteer · retrieved September 27, 2026
Land area587.1 mi²
Water area9.132 mi²
Population (2025)23,934
People per mi²41

County outline

Generalized outline of Ohio County, Kentucky
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Ohio County is located

Ohio County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 98.5% of Ohio County’s measured area and water for 1.5%. Its combined area converts to 1,544.2 square kilometers or approximately 381,586 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land587.0961,520.572375,741.4
Water9.13223.6525,844.5
Total596.2281,544.223381,585.9

How Ohio County compares

By original Census land area, Ohio County ranks #5 of 120 in Kentucky and #1671 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 1.919 times the Kentucky county-equivalent median of 306 square miles. It accounts for 1.5% of the combined county land area in the state.

See the complete Kentucky ranking · What counts as a county equivalent?

Population and density of Ohio County

The Census Bureau estimates that 23,934 people lived in Ohio County on July 1, 2025. That ranks #1,701 of 3,222 county equivalents nationally and #49 of 120 in Kentucky. Since the April 1, 2020 estimates base of 23,770, the population has grown by 164 (+0.7%), compared with +2.2% for Kentucky as a whole.

With 587.1 square miles of land, that is 41 people per square mile (16 per km²), placing Ohio County #1,736 nationally for density and #84 in Kentucky. The median county equivalent has 47 people per square mile; the Kentucky median is 59. Put another way, there are about 16 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate23,74723,73023,55623,76323,90023,934
Change—−17−174+207+137+34

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Ohio County

6 incorporated places lie at least partly in Ohio County. Together they are home to 7,709 people (32.2%); the other 16,225 (67.8%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Beaver Dam city, with 3,537 residents in the county. The county seat, Hartford city, has 2,665 residents. Among places with at least 1,000 residents in 2020, Beaver Dam city grew fastest since then (+0%).

Incorporated placePopulation 2025Since 2020Land mi²
Beaver Dam city3,537+0%3.038
Hartford cityCounty seat2,665−0.1%2.837
Fordsville city451+1.8%0.448
Centertown city413−0.2%0.313
McHenry city378+1.6%0.647
Rockport city265+0.4%0.695

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Ohio County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Ohio County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.

ZIP codes

17 ZIP Code Tabulation Areas have land in Ohio County; 12 of them have most of their land inside the county, and the others mainly cover neighboring areas.

4011942320423284233342338423434234742349423524235442361423664236842369423704237642378

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Ohio County

Ohio County shares a land border with 7 county equivalents. It has more land than every one of them. The largest neighbor is Breckinridge County (569.7 mi²) and the smallest is Hancock County (187.7 mi²). Together with its neighbors, Ohio County forms a block of 3,448.3 mi² of land, of which it holds 17%.

Map of Ohio County and the 7 county equivalents that border it Butler County, Kentucky: 426.1 mi² landDaviess County, Kentucky: 458.4 mi² landMuhlenberg County, Kentucky: 467.3 mi² landGrayson County, Kentucky: 499.5 mi² landHancock County, Kentucky: 187.7 mi² landMcLean County, Kentucky: 252.5 mi² landBreckinridge County, Kentucky: 569.7 mi² land
Ohio County (dark) and its bordering county equivalents. Select a neighbor to open its profile. Drawn from the 2025 Census cartographic boundaries in an equal-area projection. How borders are determined.
Bordering county equivalentLand mi²Size vs. OhioCompare
Breckinridge County569.7about the sameCompare
Grayson County499.51.2× smallerCompare
Muhlenberg County467.31.3× smallerCompare
Daviess County458.41.3× smallerCompare
Butler County426.11.4× smallerCompare
McLean County252.52.3× smallerCompare
Hancock County187.73.1× smallerCompare

How big is Ohio County compared with U.S. states?

Ohio County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.8 times as much. Kentucky’s county land could hold about 67 areas the size of Ohio County.

Land area: Ohio County and the closest-sized states
Ohio County587.1 mi²
Rhode Island1,033.9 mi²

Another way to picture it: the same land area would fill a square about 24.2 miles (39 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Ohio County?

Ohio County has more land than 1,551 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Ohio County587.1 mi²
Kentucky median306 mi²
National median604.5 mi²

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Ohio County at #1,756 nationally by total area, 85 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 1.5%, compared with a national county-equivalent median of 1.2% — 0.4 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Ohio County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#1670Howard County, Arkansas587.3Compare
#1671Ohio County, Kentucky587.1This county
#1672Canyon County, Idaho587Compare

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.

Representative coordinates

The Census internal point is 37.478235, -86.840642. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.

Source and precision

U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,520,571,185 m²; AWATER: 23,650,880 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How big is Ohio County?

Ohio County, Kentucky has 587.1 square miles (1,520.6 km²) of land and 9.132 square miles of water, for a total area of 596.2 square miles. It ranks #1671 of 3,222 U.S. county equivalents by land area.

Is Ohio County the largest county in Kentucky?

No. Ohio County ranks #5 of 120 in Kentucky by land area. The largest is Pike County, with 786.2 square miles of land.

What counties border Ohio County?

Ohio County shares a land border with Butler County, Daviess County, Muhlenberg County, Grayson County, Hancock County, McLean County, and Breckinridge County.

What is the population of Ohio County?

The Census Bureau estimates Ohio County had 23,934 residents on July 1, 2025, ranking #1,701 of 3,222 county equivalents. That is 41 people per square mile of land.

What is the county seat of Ohio County?

The county seat of Ohio County is Hartford.

What cities and towns are in Ohio County?

Ohio County has 6 incorporated places. The most populous five are Beaver Dam city, Hartford city, Fordsville city, Centertown city, and McHenry city; 16,225 residents live outside any incorporated place.

Is Ohio County part of a metropolitan area?

No. Ohio County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.

How many ZIP codes are in Ohio County?

17 ZIP Code Tabulation Areas have land in Ohio County, and 12 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

How does Ohio County compare with U.S. states?

It has less land than every state. Rhode Island, the smallest, has 1.8 times as much land.

How many acres of land are in Ohio County?

The land measurement converts to approximately 375,741 acres. Including water, total area is approximately 381,586 acres. One square mile equals 640 acres.

Why might another source show a different area?

Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.

Can this establish a property boundary?

No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.

Cite this county

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