Madison County area

Population and density of Madison County

The Census Bureau estimates that 263,110 people lived in Madison County on July 1, 2025. That ranks #284 of 3,222 county equivalents nationally and #8 of 102 in Illinois. Since the April 1, 2020 estimates base of 265,983, the population has declined by 2,873 (−1.1%), compared with −0.8% for Illinois as a whole.

With 715.5 square miles of land, that is 368 people per square mile (142 per km²), placing Madison County #438 nationally for density and #10 in Illinois. The median county equivalent has 47 people per square mile; the Illinois median is 44. Put another way, there are about 1.7 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 Madison County

29 incorporated places lie at least partly in Madison County. Together they are home to 207,772 people (79%); the other 55,338 (21%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Granite City city, with 26,807 residents in the county. The county seat, Edwardsville city, has 26,463 residents. By land, Godfrey village is the largest at 34.4 mi². Among places with at least 1,000 residents in 2020, Troy city grew fastest since then (+4.1%).

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

Metropolitan area

Madison County is a central county of the St. Louis, MO-IL Metropolitan Statistical Area. Its 15 county equivalents have 2,814,421 residents on 7,863.5 square miles of land; Madison County accounts for 9.1% of the land and 9.3% of the residents. By combined land it ranks #19 of 393 metropolitan areas, and #23 by population. It belongs to the St. Louis-St. Charles-Farmington, MO-IL Combined Statistical Area.

ZIP codes

36 ZIP Code Tabulation Areas have land in Madison County; 28 of them have most of their land inside the county, and the others mainly cover neighboring areas.

620016200262010620126201862021620246202562026620346203562040620466204862058620606206162062620676207462084620866208762088620906209562097622016221662234622496225462275622816229362294

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 Madison County

Madison County shares a land border with 9 county equivalents, including 3 in Missouri. It has more land than 8 of them. The largest neighbor is Macoupin County (863 mi²) and the smallest is St. Louis city (61.7 mi²). Together with its neighbors, Madison County forms a block of 5,294.4 mi² of land, of which it holds 13.5%.

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

Madison County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Illinois’s county land could hold about 78 areas the size of Madison County.

Another way to picture it: the same land area would fill a square about 26.7 miles (43 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 Madison County?

Madison County has more land than 1,952 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 Madison County at #1,304 nationally by total area, 34 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 3.3%, compared with a national county-equivalent median of 1.2% — 2.1 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 Madison 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.