The map above shows Illinois and Kansas side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Kansas Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while Kansas has 81,759 square miles (211,754 km²). Kansas' land area is 1.5 times (47%) larger than Illinois'.
Total area: Illinois: 57,913 square miles (149,995 km²) vs Kansas: 82,278 square miles (213,100 km²), including inland and coastal water. Kansas' total area is 1.4 times (42%) larger than Illinois'.
Length: Illinois is 390 miles (628 km) long from north to south; Kansas is 207 miles (334 km). Illinois' north-south length is 1.9 times (88%) longer than Kansas'.
Width: Illinois spans 283 miles (456 km) east to west; Kansas spans 401 miles (645 km). Kansas' east-west width is 1.4 times (42%) wider than Illinois'.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); Kansas's is Mount Sunflower at 4,040 feet (1,231 m). Mount Sunflower is 2,808 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; Kansas's is Verdigris River at 679 feet. Illinois's lowest point is 387 feet lower.
Illinois vs Kansas Population and History
Population: Illinois has a population of 12,710,158 (2024), while Kansas has 2,970,606 (2024). Illinois' population is 4.3 times (328%) larger than Kansas'.
Population density: Illinois: 229.0 people per square mile vs Kansas: 36.3. Illinois' population density is 6.3 times (531%) higher than Kansas'.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; Kansas's is Wichita with 400,991. Chicago's population is 6.8 times (579%) larger than Wichita's.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Kansas's Kansas City, MO-KS metro area (2,253,579). Chicago-Naperville-Elgin, IL-IN metro area's population is 4.2 times (317%) larger than Kansas City, MO-KS metro area's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. Kansas: Admitted to the Union on January 29, 1861, as the 34th state. In its current form, Illinois is the older of the two by 43 years.
Illinois vs Kansas Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs Kansas's $230.5 billion. Illinois' economic output is 5.0 times (398%) larger than Kansas'.
GDP per capita: Illinois: $90,330 per person vs Kansas: $77,601. Illinois' GDP per capita is 1.2 times (16%) higher than Kansas'.
Average income: Illinois: $74,522 vs Kansas: $65,856 average income per person (per capita personal income). Illinois' average income is 1.1 times (13%) higher than Kansas'.
Illinois vs Kansas Counties
Number of counties: Illinois has 102 counties, while Kansas has 105. Illinois and Kansas have about the same county count.
Biggest county by area: Illinois's largest county is McLean County at 1,183 square miles; Kansas's is Butler County at 1,430 square miles. Butler County's land area is 1.2 times (21%) larger than McLean County's.
Smallest county by area: Illinois: Putnam County (160 sq mi) vs Kansas: Wyandotte County (152 sq mi). Putnam County's land area is 1.1 times (6%) larger than Wyandotte County's.
Most populous county: Illinois: Cook County (5,182,617 people) vs Kansas: Johnson County (632,276 people). Cook County's population is 8.2 times (720%) larger than Johnson County's.
Least populous county: Illinois: Hardin County (3,550 people) vs Kansas: Greeley County (1,152 people). Hardin County's population is 3.1 times (208%) larger than Greeley County's.
Richest county: Illinois: Cumberland County ($104,890 per capita income) vs Kansas: Greeley County ($134,780). Greeley County's income is 1.3 times (28%) richer than Cumberland County's.
Poorest county: Illinois: Lawrence County ($43,606 per capita income) vs Kansas: Wyandotte County ($42,878). Lawrence County and Wyandotte County have about the same income.
Illinois vs Kansas Taxes
State income tax: Illinois has a top income tax rate of 4.95%, while Kansas has a top income tax rate of 5.58%. Kansas's top rate is 0.63 percentage points higher.
Property tax: Illinois: 1.92% effective rate vs Kansas: 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 Kansas: 8.71%. Illinois's combined rate is 0.27 percentage points higher.
Official Websites
Illinois official website · Kansas official website
More Size Comparisons
All Illinois size comparisons · All Kansas 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.