The map above shows Illinois and Missouri side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Missouri Geography
Land area
- Illinois has a land area of 55,513 square miles (143,778 km²), while Missouri has 68,746 square miles (178,052 km²).
- Missouri's land area is 1.2 times (24%) larger than Illinois'.
Total area
- Illinois: 57,913 square miles (149,995 km²) vs Missouri: 69,707 square miles (180,540 km²), including inland and coastal water.
- Missouri's total area is 1.2 times (20%) larger than Illinois'.
Length
- Illinois is 390 miles (628 km) long from north to south; Missouri is 328 miles (529 km).
- Illinois' north-south length is 1.2 times (19%) longer than Missouri's.
Width
- Illinois spans 283 miles (456 km) east to west; Missouri spans 437 miles (703 km).
- Missouri's east-west width is 1.5 times (54%) wider than Illinois'.
Highest point
- Illinois's highest point is Charles Mound at 1,232 feet (376 m); Missouri's is Taum Sauk Mountain at 1,771 feet (540 m).
- Taum Sauk Mountain is 539 feet higher than Charles Mound.
Lowest point
- Illinois's lowest point is Mississippi River at 292 feet; Missouri's is St. Francis River at 230 feet.
- Missouri's lowest point is 62 feet lower.
Illinois vs Missouri Population and History
Population
- Illinois has a population of 12,710,158 (2024), while Missouri has 6,245,466 (2024).
- Illinois' population is 2.0 times (104%) larger than Missouri's.
Population density
- Illinois: 229.0 people per square mile vs Missouri: 90.8.
- Illinois' population density is 2.5 times (152%) higher than Missouri's.
Biggest city
- Illinois's biggest city is Chicago with 2,721,308 people; Missouri's is Kansas City with 516,032.
- Chicago's population is 5.3 times (427%) larger than Kansas City's.
Largest metro area
- Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Missouri's St. Louis, MO-IL metro area (2,811,927).
- Chicago-Naperville-Elgin, IL-IN metro area's population is 3.3 times (235%) larger than St. Louis, MO-IL metro area's.
History
- Illinois: Admitted to the Union on December 3, 1818, as the 21st state.
- Missouri: Admitted to the Union on August 10, 1821, as the 24th state.
- In its current form, Illinois is the older of the two by 3 years.
Illinois vs Missouri Economy
GDP
- Illinois's GDP is $1,148.1 billion (2024) vs Missouri's $448.7 billion.
- Illinois' economic output is 2.6 times (156%) larger than Missouri's.
GDP per capita
- Illinois: $90,330 per person vs Missouri: $71,846.
- Illinois' GDP per capita is 1.3 times (26%) higher than Missouri's.
Average income
- Illinois: $74,522 vs Missouri: $64,920 average income per person (per capita personal income).
- Illinois' average income is 1.1 times (15%) higher than Missouri's.
Illinois vs Missouri Counties
Number of counties
- Illinois has 102 counties, while Missouri has 115.
- Missouri's county count is 1.1 times (13%) higher than Illinois'.
Biggest county by area
- Illinois's largest county is McLean County at 1,183 square miles; Missouri's is Texas County at 1,177 square miles.
- McLean County and Texas County have about the same land area.
Smallest county by area
- Illinois: Putnam County (160 sq mi) vs Missouri: St. Louis city (62 sq mi).
- Putnam County's land area is 2.6 times (159%) larger than St. Louis city's.
Most populous county
- Illinois: Cook County (5,182,617 people) vs Missouri: St. Louis County (992,929 people).
- Cook County's population is 5.2 times (422%) larger than St. Louis County's.
Least populous county
- Illinois: Hardin County (3,550 people) vs Missouri: Worth County (1,872 people).
- Hardin County's population is 1.9 times (90%) larger than Worth County's.
Richest county
- Illinois: Cumberland County ($104,890 per capita income) vs Missouri: St. Louis County ($104,775).
- Cumberland County and St. Louis County have about the same income.
Poorest county
- Illinois: Lawrence County ($43,606 per capita income) vs Missouri: Douglas County ($40,515).
- Lawrence County's income is 1.1 times (8%) richer than Douglas County's.
Illinois vs Missouri Taxes
State income tax
- Illinois has a top income tax rate of 4.95%, while Missouri has a top income tax rate of 4.7%.
- Illinois's top rate is 0.25 percentage points higher.
Property tax
- Illinois: 1.92% effective rate vs Missouri: 0.79% of home value per year.
- Illinois's rate is 1.13 percentage points higher.
Sales tax
- Illinois: 8.98% combined state and average local rate vs Missouri: 8.44%.
- Illinois's combined rate is 0.54 percentage points higher.
Official Websites
Illinois official website · Missouri official website
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More Size Comparisons
All Illinois size comparisons · All Missouri 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.