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Illinois State Information

Illinois is a midwestern state that’s the 25th largest state (in area) in the country. It’s also the sixth most populous, meaning a lot of people live there!

It’s known for forests, farmlands, wetlands, and hills. By contrast, it’s also home to Chicago, one of the largest cities in the United States, which is famous for its skyscrapers.


Quick Facts

  • Capital: Springfield
  • Population: 13 million
  • Nickname: The Prairie State
  • Key Cities: Chicago, Champaign, Peoria, Rockford, Springfield
  • Postal Abbreviation: IL
  • Major Industries: Service industry, manufacturing, agriculture, mining


How did Illinois get its name: The state of Illinois gets its name from the Illinois River, which was named by a French explorer after the Indian tribes he found living along the river’s banks.


Illinois is the French spelling for the Illinois and Peoria Indian word “iliniwok,” which means men or warriors, and perhaps refers to members of the Illinois tribe.

Date admitted to the Union: Thursday, December 3, 1818



Size: 57,915 sq. miles

Lowest point: Mississippi River at 279 feet

Highest point: Charles Mound at 1,235 feet

Counties: 102

Famous locations: Willis Tower Sky Deck (Sears Tower), Cloud Gate, Abraham Lincoln Presidential Library and Museum, Starved Rock State Park


Famous Illinoisans

Cindy Crawford- model

Robin Williams- actor and comedian

Harrison Ford- actor

Mrs. Doubtfire

Bernie Mac- comedian

Carl Sandburg- poet

Terrence Howard- actor

Fun Facts

Alton, Illinois was once home to Robert Pershing Wadlow, the world’s tallest man, who was born in 1918. He grew to be eight feet and 11 inches tall, and he wore size 37 shoes!

Robert Wadlow

He was known as the ‘Alton Giant’.

Illinois is a great place for sweet treats. The first Dairy Queen opened in 1940 in the city of Joliet, and the world’s largest cookie factory is located in Chicago.


In 1995, Nabisco made 16 billion Oreos in the factory. Plus, the ice cream sundae was invented in Evanston, Illinois.


The Chicago River is one of the only rivers in the world that flows backwards. Each year for St. Patrick’s Day, the river is dyed green!

In 1865, Illinois became the first state to ratify (officially accept) the 13th amendment abolishing slavery.

The world’s largest public library can be found in Chicago. The Chicago Public Library holds over 2 million books!

Chicago Public Library
Chicago Cultural Center, formerly the Chicago Public Library building.

Morton, Illinois is known as the “pumpkin capital of the world.” More than 85% of packaged pumpkins come from Morton.

More US state facts.


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