- U.S. State: Illinois
- Abbreviation: IL
- Joined the USA: December 3rd, 1818 (21st State)
- Located: Midwestern United States
- Capital City: Springfield, IL
- Most Populated City: Chicago, IL
34 Illinois Facts for School
- Illinois is a state in the United States of America.
- Illinois is in the midwestern region of the United States.
- Illinois became a U.S. state on Thursday, December 3rd, 1818.
- Illinois was the 21st state to join the United States.
- The U.S. state of Illinois covers 57,915 square miles.
- Illinois is the 25th largest state by area in the United States.
- In 2019, the population of Illinois was estimated to be 12,670,000 residents by the U.S. Census Bureau.
- In 2019, Illinois was the 6th most populated state in the United States.
- A person who is from or lives in Illinois is called an Illinoisan.
- The capital city of Illinois is Springfield.
- The eight most populated cities in Illinois are Chicago, Aurora, Rockford, Juliet, Naperville, Springfield, Peoria and Elgin.
- The largest city by population in Illinois is Chicago.
- The largest metropolitan area in Illinois is the Chicagoland area.
- The U.S. state of Illinois has 102 counties.
- The most populated county in Illinois is Cook County with 5,150,000 residents (2019, U.S. Census Bureau).
- The largest county by area in Illinois is McLean County with 1,184 square miles.
- The highest elevation point in Illinois is Charles Mound at 1,235 feet above sea level
- The lowest elevation point in Illinois is the confluence of Mississippi and Ohio River at 280 feet above sea level.
- The average precipitation (rain and snow) in Illinois is 38.52 inches.
- Illinois is the 30th wettest state by precipitation (rain and snow) in the United States.
- The average temperature in Illinois is 51.3 °F.
- The warmest temperature ever recorded in Illinois was 117 °F on July 14th, 1954.
- The coldest temperature ever recorded in Illinois was -38 °F on January 31st, 2019.
- A few natural disasters that can affect Illinois are blizzards, earthquakes, hail, heat waves, ice storms, river flooding, thunderstorms and tornadoes.
- Illinois is in one time zone, Central Time Zone (CT).
- The USPS abbreviation for Illinois is IL.
- The nickname for the U.S. state of Illinois is the “Prairie State”.
- Illinois is also known as the “Land of Lincoln”, to honor past U.S. president Abraham Lincoln.
- The official state flower of Illinois is the violet (Violaceae).
- The official state tree of Illinois is the white oak (Quercus alba).
- The official state insect of Illinois is the monarch butterfly (Danaus plexippus)
- The official state bird of Illinois is the cardinal (Cardinalidae).
- The official state fish of Illinois is the bluegill (Lepomis macrochirus).
- The official state animal of Illinois is the white-tailed deer (Odocoileus virginianus).
Pictures of Illinois
A picture of the flag for the U.S. state of Illinois.
A picture of Springfield, the capital city of Illinois.
A picture of Chicago, the most populated city in Illinois.
Additional Resources on Illinois
- About Illinois – Learn more about the U.S. state of Illinois on the Illinois State Government website.
- History of Illinois – Discover the history of Illinois on the Illinois Courts website.
- Facts About Illinois – Find more facts about Illinois on the National Geographic for School website.
- Illinois – Britannica – Read the Britannica entry on the U.S. state of Illinois to learn more about it.