The map above shows Colorado and Illinois side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Colorado vs Illinois Geography
Land area
- Colorado has a land area of 103,637 square miles (268,419 km²), while Illinois has 55,513 square miles (143,778 km²).
- Colorado's land area is 1.9 times (87%) larger than Illinois'.
Total area
- Colorado: 104,095 square miles (269,605 km²) vs Illinois: 57,913 square miles (149,995 km²), including inland and coastal water.
- Colorado's total area is 1.8 times (80%) larger than Illinois'.
Length
- Colorado is 467 miles (751 km) long from north to south; Illinois is 390 miles (628 km).
- Colorado's north-south length is 1.2 times (20%) longer than Illinois'.
Width
- Colorado spans 387 miles (622 km) east to west; Illinois spans 283 miles (456 km).
- Colorado's east-west width is 1.4 times (37%) wider than Illinois'.
Highest point
- Colorado's highest point is Mount Elbert at 14,422 feet (4,396 m); Illinois's is Charles Mound at 1,232 feet (376 m).
- Mount Elbert is 13,190 feet higher than Charles Mound.
Lowest point
- Colorado's lowest point is Arikaree River at 3,326 feet; Illinois's is Mississippi River at 292 feet.
- Illinois's lowest point is 3,034 feet lower.
Colorado vs Illinois Population and History
Population
- Colorado has a population of 5,957,493 (2024), while Illinois has 12,710,158 (2024).
- Illinois' population is 2.1 times (113%) larger than Colorado's.
Population density
- Colorado: 57.5 people per square mile vs Illinois: 229.0.
- Illinois' population density is 4.0 times (298%) higher than Colorado's.
Biggest city
- Colorado's biggest city is Denver with 729,019 people; Illinois's is Chicago with 2,721,308.
- Chicago's population is 3.7 times (273%) larger than Denver's.
Largest metro area
- Colorado's largest metropolitan area is Denver-Aurora-Centennial, CO metro area (3,052,498 people) vs Illinois's Chicago-Naperville-Elgin, IL-IN metro area (9,408,576).
- Chicago-Naperville-Elgin, IL-IN metro area's population is 3.1 times (208%) larger than Denver-Aurora-Centennial, CO metro area's.
History
- Colorado: Admitted to the Union on August 1, 1876, as the 38th state.
- Illinois: Admitted to the Union on December 3, 1818, as the 21st state.
- In its current form, Illinois is the older of the two by 58 years.
Colorado vs Illinois Economy
GDP
- Colorado's GDP is $557.6 billion (2024) vs Illinois's $1,148.1 billion.
- Illinois' economic output is 2.1 times (106%) larger than Colorado's.
GDP per capita
- Colorado: $93,602 per person vs Illinois: $90,330.
- Colorado and Illinois have about the same GDP per capita.
Average income
- Colorado: $83,055 vs Illinois: $74,522 average income per person (per capita personal income).
- Colorado's average income is 1.1 times (11%) higher than Illinois'.
Colorado vs Illinois Counties
Number of counties
- Colorado has 64 counties, while Illinois has 102.
- Illinois' county count is 1.6 times (59%) higher than Colorado's.
Biggest county by area
- Colorado's largest county is Las Animas County at 4,773 square miles; Illinois's is McLean County at 1,183 square miles.
- Las Animas County's land area is 4.0 times (303%) larger than McLean County's.
Smallest county by area
- Colorado: Broomfield County (33 sq mi) vs Illinois: Putnam County (160 sq mi).
- Putnam County's land area is 4.9 times (385%) larger than Broomfield County's.
Most populous county
- Colorado: El Paso County (752,772 people) vs Illinois: Cook County (5,182,617 people).
- Cook County's population is 6.9 times (588%) larger than El Paso County's.
Least populous county
- Colorado: Hinsdale County (747 people) vs Illinois: Hardin County (3,550 people).
- Hardin County's population is 4.8 times (375%) larger than Hinsdale County's.
Richest county
- Colorado: Pitkin County ($275,044 per capita income) vs Illinois: Cumberland County ($104,890).
- Pitkin County's income is 2.6 times (162%) richer than Cumberland County's.
Poorest county
- Colorado: Crowley County ($27,232 per capita income) vs Illinois: Lawrence County ($43,606).
- Lawrence County's income is 1.6 times (60%) richer than Crowley County's.
Colorado vs Illinois Taxes
State income tax
- Colorado has a top income tax rate of 4.4%, while Illinois has a top income tax rate of 4.95%.
- Illinois's top rate is 0.55 percentage points higher.
Property tax
- Colorado: 0.49% effective rate vs Illinois: 1.92% of home value per year.
- Illinois's rate is 1.43 percentage points higher.
Sales tax
- Colorado: 7.89% combined state and average local rate vs Illinois: 8.98%.
- Illinois's combined rate is 1.09 percentage points higher.
Official Websites
Colorado official website · Illinois official website
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More Size Comparisons
All Colorado size comparisons · All Illinois 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.