Dearborn County area

Population and density of Dearborn County

The Census Bureau estimates that 51,609 people lived in Dearborn County on July 1, 2025. That ranks #1,003 of 3,222 county equivalents nationally and #28 of 92 in Indiana. Since the April 1, 2020 estimates base of 50,676, the population has grown by 933 (+1.8%), compared with +2.8% for Indiana as a whole.

With 305.1 square miles of land, that is 169 people per square mile (65 per km²), placing Dearborn County #710 nationally for density and #25 in Indiana. The median county equivalent has 47 people per square mile; the Indiana median is 88. Put another way, there are about 3.8 acres of land per resident.

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 Dearborn County

7 incorporated places lie at least partly in Dearborn County. Together they are home to 16,449 people (31.9%); the other 35,160 (68.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Lawrenceburg city, with 5,243 residents in the county. By land, St. Leon town is the largest at 6.827 mi². Among places with at least 1,000 residents in 2020, Lawrenceburg city grew fastest since then (+2.2%).

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

Metropolitan area

Dearborn County is an outlying county of the Cincinnati, OH-KY-IN Metropolitan Statistical Area. Its 15 county equivalents have 2,312,858 residents on 4,385.2 square miles of land; Dearborn County accounts for 7% of the land and 2.2% of the residents. By combined land it ranks #60 of 393 metropolitan areas, and #30 by population. It belongs to the Cincinnati-Wilmington, OH-KY-IN Combined Statistical Area.

ZIP codes

9 ZIP Code Tabulation Areas have land in Dearborn County; 6 of them have most of their land inside the county, and the others mainly cover neighboring areas.

470014701247018470224702547031470324704147060

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 Dearborn County

Dearborn County shares a land border with 5 county equivalents, including 2 in Ohio and Kentucky. It has more land than 2 of them. The largest neighbor is Ripley County (446.4 mi²) and the smallest is Ohio County (86.2 mi²). Together with its neighbors, Dearborn County forms a block of 1,873.8 mi² of land, of which it holds 16.3%.

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

Dearborn County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 3.4 times as much. Indiana’s county land could hold about 117 areas the size of Dearborn County.

Another way to picture it: the same land area would fill a square about 17.5 miles (28.1 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 Dearborn County?

Dearborn County has more land than 420 of the other 3,221 county equivalents in the dataset.

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 Dearborn County at #2,833 nationally by total area, 31 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 0.8%, compared with a national county-equivalent median of 1.2% — 0.4 percentage points lower. 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 Dearborn County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

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.