The map above shows Illinois and Wisconsin side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Wisconsin Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while Wisconsin has 54,168 square miles (140,294 km²). Illinois and Wisconsin have about the same land area.
Total area: Illinois: 57,913 square miles (149,995 km²) vs Wisconsin: 65,497 square miles (169,636 km²), including inland and coastal water. Wisconsin's total area is 1.1 times (13%) larger than Illinois'.
Length: Illinois is 390 miles (628 km) long from north to south; Wisconsin is 368 miles (593 km). Illinois' north-south length is 1.1 times (6%) longer than Wisconsin's.
Width: Illinois spans 283 miles (456 km) east to west; Wisconsin spans 323 miles (521 km). Wisconsin's east-west width is 1.1 times (14%) wider than Illinois'.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); Wisconsin's is Timms Hill at 1,946 feet (593 m). Timms Hill is 714 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; Wisconsin's is Lake Michigan at 577 feet. Illinois's lowest point is 285 feet lower.
Illinois vs Wisconsin Population and History
Population: Illinois has a population of 12,710,158 (2024), while Wisconsin has 5,960,975 (2024). Illinois' population is 2.1 times (113%) larger than Wisconsin's.
Population density: Illinois: 229.0 people per square mile vs Wisconsin: 110.0. Illinois' population density is 2.1 times (108%) higher than Wisconsin's.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; Wisconsin's is Milwaukee with 563,531. Chicago's population is 4.8 times (383%) larger than Milwaukee's.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Wisconsin's Minneapolis-St. Paul-Bloomington, MN-WI metro area (3,757,952). Chicago-Naperville-Elgin, IL-IN metro area's population is 2.5 times (150%) larger than Minneapolis-St. Paul-Bloomington, MN-WI metro area's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. Wisconsin: Admitted to the Union on May 29, 1848, as the 30th state. In its current form, Illinois is the older of the two by 30 years.
Illinois vs Wisconsin Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs Wisconsin's $453.3 billion. Illinois' economic output is 2.5 times (153%) larger than Wisconsin's.
GDP per capita: Illinois: $90,330 per person vs Wisconsin: $76,044. Illinois' GDP per capita is 1.2 times (19%) higher than Wisconsin's.
Average income: Illinois: $74,522 vs Wisconsin: $67,755 average income per person (per capita personal income). Illinois' average income is 1.1 times (10%) higher than Wisconsin's.
Illinois vs Wisconsin Counties
Number of counties: Illinois has 102 counties, while Wisconsin has 72. Illinois' county count is 1.4 times (42%) higher than Wisconsin's.
Biggest county by area: Illinois's largest county is McLean County at 1,183 square miles; Wisconsin's is Marathon County at 1,545 square miles. Marathon County's land area is 1.3 times (31%) larger than McLean County's.
Smallest county by area: Illinois: Putnam County (160 sq mi) vs Wisconsin: Pepin County (232 sq mi). Pepin County's land area is 1.4 times (45%) larger than Putnam County's.
Most populous county: Illinois: Cook County (5,182,617 people) vs Wisconsin: Milwaukee County (924,740 people). Cook County's population is 5.6 times (460%) larger than Milwaukee County's.
Least populous county: Illinois: Hardin County (3,550 people) vs Wisconsin: Menominee County (4,286 people). Menominee County's population is 1.2 times (21%) larger than Hardin County's.
Richest county: Illinois: Cumberland County ($104,890 per capita income) vs Wisconsin: Ozaukee County ($109,947). Ozaukee County's income is 1.0 times (5%) richer than Cumberland County's.
Poorest county: Illinois: Lawrence County ($43,606 per capita income) vs Wisconsin: Menominee County ($43,696). Lawrence County and Menominee County have about the same income.
Illinois vs Wisconsin Taxes
State income tax: Illinois has a top income tax rate of 4.95%, while Wisconsin has a top income tax rate of 7.65%. Wisconsin's top rate is 2.7 percentage points higher.
Property tax: Illinois: 1.92% effective rate vs Wisconsin: 1.25% of home value per year. Illinois's rate is 0.67 percentage points higher.
Sales tax: Illinois: 8.98% combined state and average local rate vs Wisconsin: 5.72%. Illinois's combined rate is 3.26 percentage points higher.
Official Websites
Illinois official website · Wisconsin official website
More Size Comparisons
All Illinois size comparisons · All Wisconsin size comparisons
Area, elevation and boundary figures come from official national statistics and US Census Bureau and Natural Earth boundary data; US state population, economic, county and tax figures come from the US Census Bureau, the Bureau of Economic Analysis and the Tax Foundation. Figures are rounded and for general reference.