Stephenson County area

Population and density of Stephenson County

The Census Bureau estimates that 43,220 people lived in Stephenson County on July 1, 2025. That ranks #1,149 of 3,222 county equivalents nationally and #33 of 102 in Illinois. Since the April 1, 2020 estimates base of 44,696, the population has declined by 1,476 (−3.3%), compared with −0.8% for Illinois as a whole.

With 564.2 square miles of land, that is 77 people per square mile (30 per km²), placing Stephenson County #1,191 nationally for density and #31 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 8.4 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 Stephenson County

11 incorporated places lie at least partly in Stephenson County. Together they are home to 30,173 people (69.8%); the other 13,047 (30.2%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Freeport city, with 23,202 residents in the county.

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

Metropolitan area

Stephenson County is a central county of the Freeport, IL Micropolitan Statistical Area. Stephenson County is the area’s only county equivalent, so the micro area has the same 564.2 square miles of land. By combined land it ranks #385 of 542 micropolitan areas, and #291 by population. It belongs to the Rockford-Freeport-Rochelle, IL Combined Statistical Area.

ZIP codes

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

61007610136101861019610276103261039610446104761048610506106061062610636106761070610786108761089

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 Stephenson County

Stephenson County shares a land border with 6 county equivalents, including 2 in Wisconsin. It has more land than 2 of them. The largest neighbor is Ogle County (758.7 mi²) and the smallest is Carroll County (445.4 mi²). Together with its neighbors, Stephenson County forms a block of 4,099.9 mi² of land, of which it holds 13.8%.

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

Stephenson 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. Illinois’s county land could hold about 98 areas the size of Stephenson County.

Another way to picture it: the same land area would fill a square about 23.8 miles (38.2 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 Stephenson County?

Stephenson County has more land than 1,401 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 Stephenson County at #1,954 nationally by total area, 133 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 0.1%, compared with a national county-equivalent median of 1.2% — 1.1 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 Stephenson 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.