DeKalb County area

Population and density of DeKalb County

The Census Bureau estimates that 44,535 people lived in DeKalb County on July 1, 2025. That ranks #1,122 of 3,222 county equivalents nationally and #35 of 92 in Indiana. Since the April 1, 2020 estimates base of 43,262, the population has grown by 1,273 (+2.9%), compared with +2.8% for Indiana as a whole.

With 362.8 square miles of land, that is 123 people per square mile (47 per km²), placing DeKalb County #863 nationally for density and #31 in Indiana. The median county equivalent has 47 people per square mile; the Indiana median is 88. Put another way, there are about 5.2 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 DeKalb County

9 incorporated places lie at least partly in DeKalb County. Together they are home to 27,417 people (61.6%); the other 17,118 (38.4%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Auburn city, with 14,068 residents in the county. Among places with at least 1,000 residents in 2020, Auburn city grew fastest since then (+4%).

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

Metropolitan area

DeKalb County is a central county of the Auburn, IN Micropolitan Statistical Area. DeKalb County is the area’s only county equivalent, so the micro area has the same 362.8 square miles of land. By combined land it ranks #507 of 542 micropolitan areas, and #280 by population. It belongs to the Fort Wayne-Huntington-Auburn, IN Combined Statistical Area.

ZIP codes

14 ZIP Code Tabulation Areas have land in DeKalb County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.

4670546706467104672146730467384674246747467484675546763467854678846793

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 DeKalb County

DeKalb County shares a land border with 5 county equivalents, including 2 in Ohio. It has more land than 1 of them. The largest neighbor is Allen County (657.1 mi²) and the smallest is Steuben County (308.8 mi²). Together with its neighbors, DeKalb County forms a block of 2,571.7 mi² of land, of which it holds 14.1%.

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

DeKalb County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.8 times as much. Indiana’s county land could hold about 99 areas the size of DeKalb County.

Another way to picture it: the same land area would fill a square about 19 miles (30.7 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 DeKalb County?

DeKalb County has more land than 576 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 DeKalb County at #2,697 nationally by total area, 51 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 0.3%, compared with a national county-equivalent median of 1.2% — 0.9 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 DeKalb 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.