The map above shows Illinois and Massachusetts side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Massachusetts Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while Massachusetts has 7,801 square miles (20,204 km²). Illinois' land area is 7.1 times (612%) larger than Massachusetts'.
Total area: Illinois: 57,913 square miles (149,995 km²) vs Massachusetts: 10,554 square miles (27,335 km²), including inland and coastal water. Illinois' total area is 5.5 times (449%) larger than Massachusetts'.
Length: Illinois is 390 miles (628 km) long from north to south; Massachusetts is 123 miles (198 km). Illinois' north-south length is 3.2 times (217%) longer than Massachusetts'.
Width: Illinois spans 283 miles (456 km) east to west; Massachusetts spans 185 miles (297 km). Illinois' east-west width is 1.5 times (53%) wider than Massachusetts'.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); Massachusetts's is Mount Greylock at 3,489 feet (1,063 m). Mount Greylock is 2,257 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; Massachusetts's is Atlantic Ocean at 0 feet. Massachusetts's lowest point is 292 feet lower.
Illinois vs Massachusetts Population and History
Population: Illinois has a population of 12,710,158 (2024), while Massachusetts has 7,136,171 (2024). Illinois' population is 1.8 times (78%) larger than Massachusetts'.
Population density: Illinois: 229.0 people per square mile vs Massachusetts: 914.8. Massachusetts' population density is 4.0 times (299%) higher than Illinois'.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; Massachusetts's is Boston with 673,458. Chicago's population is 4.0 times (304%) larger than Boston's.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Massachusetts's Boston-Cambridge-Newton, MA-NH metro area (5,025,517). Chicago-Naperville-Elgin, IL-IN metro area's population is 1.9 times (87%) larger than Boston-Cambridge-Newton, MA-NH metro area's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. Massachusetts: Admitted to the Union on February 6, 1788, as the 6th state. In its current form, Massachusetts is the older of the two by 30 years.
Illinois vs Massachusetts Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs Massachusetts's $778.5 billion. Illinois' economic output is 1.5 times (47%) larger than Massachusetts'.
GDP per capita: Illinois: $90,330 per person vs Massachusetts: $109,095. Massachusetts' GDP per capita is 1.2 times (21%) higher than Illinois'.
Average income: Illinois: $74,522 vs Massachusetts: $93,607 average income per person (per capita personal income). Massachusetts' average income is 1.3 times (26%) higher than Illinois'.
Illinois vs Massachusetts Counties
Number of counties: Illinois has 102 counties, while Massachusetts has 14. Illinois' county count is 7.3 times (629%) higher than Massachusetts'.
Biggest county by area: Illinois's largest county is McLean County at 1,183 square miles; Massachusetts's is Worcester County at 1,511 square miles. Worcester County's land area is 1.3 times (28%) larger than McLean County's.
Smallest county by area: Illinois: Putnam County (160 sq mi) vs Massachusetts: Nantucket County (46 sq mi). Putnam County's land area is 3.5 times (247%) larger than Nantucket County's.
Most populous county: Illinois: Cook County (5,182,617 people) vs Massachusetts: Middlesex County (1,668,956 people). Cook County's population is 3.1 times (211%) larger than Middlesex County's.
Least populous county: Illinois: Hardin County (3,550 people) vs Massachusetts: Nantucket County (14,670 people). Nantucket County's population is 4.1 times (313%) larger than Hardin County's.
Richest county: Illinois: Cumberland County ($104,890 per capita income) vs Massachusetts: Nantucket County ($129,250). Nantucket County's income is 1.2 times (23%) richer than Cumberland County's.
Poorest county: Illinois: Lawrence County ($43,606 per capita income) vs Massachusetts: Hampshire County ($65,432). Hampshire County's income is 1.5 times (50%) richer than Lawrence County's.
Illinois vs Massachusetts Taxes
State income tax: Illinois has a top income tax rate of 4.95%, while Massachusetts has a top income tax rate of 9%. Massachusetts's top rate is 4.05 percentage points higher.
Property tax: Illinois: 1.92% effective rate vs Massachusetts: 1% of home value per year. Illinois's rate is 0.92 percentage points higher.
Sales tax: Illinois: 8.98% combined state and average local rate vs Massachusetts: 6.25%. Illinois's combined rate is 2.73 percentage points higher.
Official Websites
Illinois official website · Massachusetts official website
More Size Comparisons
All Illinois size comparisons · All Massachusetts 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.