U.S. state profile · IL
Illinois: area, population and density
Illinois has 55,514 sq mi of land and a 2025 population estimate of 12,719,141; calculated population density is 88 people/km².
Sources: U.S. Census Bureau Gazetteer Files · 2026 · U.S. Census Bureau Population Estimates Program · 2025.
Illinois ranks 24th of 51 by land area, 6th by population and 14th by calculated population density among the U.S. states and DC. Density uses the displayed population divided by land area converted to square kilometres.
- Land area
- 55,514 sq miU.S. Census Bureau Gazetteer Files · 2026
- Population
- 12,719,141U.S. Census Bureau Population Estimates Program · 2025
- Calculated density
- 88 people/km²Population ÷ land area in km²
Reading the figures
Illinois in the U.S. comparison set
Illinois has 55,514 sq mi of land area and a population estimate of 12,719,141 for 2025. In the 51-place state and DC set, it is 24th by land area, 6th by population, and 14th by calculated density.
Density is not a separately reported value here. It is calculated from the population and land area above, converted to square kilometres, so the result can be compared with supported country figures.
U.S. boundary outline: Census TIGER/Line 2025. The drawing is fitted to this profile panel; use a comparison page for a shared-area scale.