The map above shows Illinois and New Jersey side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs New Jersey Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while New Jersey has 7,355 square miles (19,049 km²). Illinois' land area is 7.5 times (655%) larger than New Jersey's.
Total area: Illinois: 57,913 square miles (149,995 km²) vs New Jersey: 8,719 square miles (22,583 km²), including inland and coastal water. Illinois' total area is 6.6 times (564%) larger than New Jersey's.
Length: Illinois is 390 miles (628 km) long from north to south; New Jersey is 169 miles (271 km). Illinois' north-south length is 2.3 times (131%) longer than New Jersey's.
Width: Illinois spans 283 miles (456 km) east to west; New Jersey spans 129 miles (207 km). Illinois' east-west width is 2.2 times (119%) wider than New Jersey's.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); New Jersey's is High Point at 1,798 feet (548 m). High Point is 566 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; New Jersey's is Atlantic Ocean at 0 feet. New Jersey's lowest point is 292 feet lower.
Illinois vs New Jersey Population and History
Population: Illinois has a population of 12,710,158 (2024), while New Jersey has 9,500,851 (2024). Illinois' population is 1.3 times (34%) larger than New Jersey's.
Population density: Illinois: 229.0 people per square mile vs New Jersey: 1,291.8. New Jersey's population density is 5.6 times (464%) higher than Illinois'.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; New Jersey's is Newark with 317,303. Chicago's population is 8.6 times (758%) larger than Newark's.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs New Jersey's New York-Newark-Jersey City, NY-NJ metro area (19,940,274). New York-Newark-Jersey City, NY-NJ metro area's population is 2.1 times (112%) larger than Chicago-Naperville-Elgin, IL-IN metro area's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. New Jersey: Admitted to the Union on December 18, 1787, as the 3rd state. In its current form, New Jersey is the older of the two by 31 years.
Illinois vs New Jersey Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs New Jersey's $846.0 billion. Illinois' economic output is 1.4 times (36%) larger than New Jersey's.
GDP per capita: Illinois: $90,330 per person vs New Jersey: $89,045. Illinois and New Jersey have about the same GDP per capita.
Average income: Illinois: $74,522 vs New Jersey: $84,893 average income per person (per capita personal income). New Jersey's average income is 1.1 times (14%) higher than Illinois'.
Illinois vs New Jersey Counties
Number of counties: Illinois has 102 counties, while New Jersey has 21. Illinois' county count is 4.9 times (386%) higher than New Jersey's.
Biggest county by area: Illinois's largest county is McLean County at 1,183 square miles; New Jersey's is Burlington County at 799 square miles. McLean County's land area is 1.5 times (48%) larger than Burlington County's.
Smallest county by area: Illinois: Putnam County (160 sq mi) vs New Jersey: Hudson County (46 sq mi). Putnam County's land area is 3.5 times (247%) larger than Hudson County's.
Most populous county: Illinois: Cook County (5,182,617 people) vs New Jersey: Bergen County (978,641 people). Cook County's population is 5.3 times (430%) larger than Bergen County's.
Least populous county: Illinois: Hardin County (3,550 people) vs New Jersey: Salem County (65,874 people). Salem County's population is 18.6 times larger than Hardin County's.
Richest county: Illinois: Cumberland County ($104,890 per capita income) vs New Jersey: Somerset County ($121,042). Somerset County's income is 1.2 times (15%) richer than Cumberland County's.
Poorest county: Illinois: Lawrence County ($43,606 per capita income) vs New Jersey: Cumberland County ($50,843). Cumberland County's income is 1.2 times (17%) richer than Lawrence County's.
Illinois vs New Jersey Taxes
State income tax: Illinois has a top income tax rate of 4.95%, while New Jersey has a top income tax rate of 10.75%. New Jersey's top rate is 5.8 percentage points higher.
Property tax: Illinois: 1.92% effective rate vs New Jersey: 1.89% of home value per year. Illinois's rate is 0.03 percentage points higher.
Sales tax: Illinois: 8.98% combined state and average local rate vs New Jersey: 6.6%. Illinois's combined rate is 2.38 percentage points higher.
Official Websites
Illinois official website · New Jersey official website
More Size Comparisons
All Illinois size comparisons · All New Jersey 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.