Sangamon County area

Population and density of Sangamon County

The Census Bureau estimates that 194,170 people lived in Sangamon County on July 1, 2025. That ranks #368 of 3,222 county equivalents nationally and #11 of 102 in Illinois. Since the April 1, 2020 estimates base of 196,405, the population has declined by 2,235 (−1.1%), compared with −0.8% for Illinois as a whole.

With 868.2 square miles of land, that is 224 people per square mile (86 per km²), placing Sangamon County #605 nationally for density and #13 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 2.9 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 Sangamon County

26 incorporated places lie at least partly in Sangamon County. Together they are home to 162,855 people (83.9%); the other 31,315 (16.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Springfield city, with 112,989 residents in the county. Among places with at least 1,000 residents in 2020, Rochester village grew fastest since then (+5.9%).

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

Metropolitan area

Sangamon County is a central county of the Springfield, IL Metropolitan Statistical Area. Its 2 county equivalents have 206,033 residents on 1,182.6 square miles of land; Sangamon County accounts for 73.4% of the land and 94.2% of the residents. By combined land it ranks #261 of 393 metropolitan areas, and #234 by population. It belongs to the Springfield-Jacksonville-Lincoln, IL Combined Statistical Area.

ZIP codes

30 ZIP Code Tabulation Areas have land in Sangamon County; 26 of them have most of their land inside the county, and the others mainly cover neighboring areas.

625156252062530625366253962545625486255862561625636261362615626256262962661626706267762684626896269062692626936270162702627036270462706627076271162712

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 Sangamon County

Sangamon County shares a land border with 8 county equivalents. It has more land than every one of them. The largest neighbor is Macoupin County (863 mi²) and the smallest is Menard County (314.4 mi²). Together with its neighbors, Sangamon County forms a block of 5,602.2 mi² of land, of which it holds 15.5%.

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

Sangamon County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.2 times as much. Illinois’s county land could hold about 64 areas the size of Sangamon County.

Another way to picture it: the same land area would fill a square about 29.5 miles (47.4 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 Sangamon County?

Sangamon County has more land than 2,278 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 Sangamon County at #1,035 nationally by total area, 91 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%, compared with a national county-equivalent median of 1.2% — 0.2 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 Sangamon 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.