Whiteside County area

Population and density of Whiteside County

The Census Bureau estimates that 54,121 people lived in Whiteside County on July 1, 2025. That ranks #972 of 3,222 county equivalents nationally and #24 of 102 in Illinois. Since the April 1, 2020 estimates base of 55,688, the population has declined by 1,567 (−2.8%), compared with −0.8% for Illinois as a whole.

With 684.1 square miles of land, that is 79 people per square mile (31 per km²), placing Whiteside County #1,169 nationally for density and #29 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 8.1 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 Whiteside County

11 incorporated places lie at least partly in Whiteside County. Together they are home to 36,001 people (66.5%); the other 18,120 (33.5%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Sterling city, with 14,394 residents in the county. The county seat, Morrison city, has 3,945 residents.

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

Metropolitan area

Whiteside County is a central county of the Sterling, IL Micropolitan Statistical Area. Whiteside County is the area’s only county equivalent, so the micro area has the same 684.1 square miles of land. By combined land it ranks #315 of 542 micropolitan areas, and #200 by population. It belongs to the Dixon-Sterling, IL Combined Statistical Area.

ZIP codes

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

610146103761064610716108161230612436125061251612526125461261612706127761283

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 Whiteside County

Whiteside County shares a land border with 7 county equivalents, including 1 in Iowa. It has more land than 2 of them. The largest neighbor is Bureau County (869.1 mi²) and the smallest is Rock Island County (427.5 mi²). Together with its neighbors, Whiteside County forms a block of 5,427.6 mi² of land, of which it holds 12.6%.

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

Whiteside County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.5 times as much. Illinois’s county land could hold about 81 areas the size of Whiteside County.

Another way to picture it: the same land area would fill a square about 26.2 miles (42.1 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 Whiteside County?

Whiteside County has more land than 1,851 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 Whiteside County at #1,449 nationally by total area, 78 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 1.8%, compared with a national county-equivalent median of 1.2% — 0.6 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 Whiteside 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.