Mercer County, IL Demographics
Mercer County, IL is the 69th most populous of 102 counties in Illinois, with 15,699 residents across 561 square miles. That is about 28 people per square mile.
At the 2020 census
| Population | 15,699 |
|---|---|
| Land area | 561 sq mi |
| Density | 28 / sq mi |
Data: 2020 Census · American Community Survey 2024
How Mercer County compares to the US
We're computing this county's comparison table — check back shortly. Population, land area, and density above are already exact.
Central Location: Mercer County, IL
Measured from the county's main population center using 2020 census blocks.
We're computing the drive-time and radius areas around Mercer County, IL — check back shortly. Meanwhile you can drop a pin anywhere in the radius tool.
Census tracts in Mercer County, IL
| Name | Population | Sq mi | Per sq mi |
|---|---|---|---|
| Census Tract 401 | 4,518 | 113.6 | 40 |
| Census Tract 404 | 3,880 | 191.5 | 20 |
| Census Tract 403 | 3,783 | 16.0 | 237 |
| Census Tract 402 | 3,518 | 240.1 | 15 |
Related places
Other counties nearby
Nearest counties
Metro areas containing Mercer County
About this page
This page shows demographics for a US county from the 2020 census and the American Community Survey: population, land area, density, urban share, and how the county compares to national averages for income, housing, age, and more.
Counties subdivide into census tracts, listed below with their populations. The drive-time and radius tables measure the population around the county's main population center.