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Updated November 30, 2023 | Infoplease Staff
Illinois flag


Illinois State Information

Capital: Springfield

Official Name: State of Illinois

Organized as a territory/republic: February 3, 1809

Entered Union (21): December 3, 1818 (21st state)

Present constitution adopted: 1970

State abbreviation/Postal code: Ill./IL

State Area Codes: 217, 224, 309, 312, 331, 618, 630, 708, 773, 779, 815, 847 and 872

Fun Facts About Illinois

Nickname: The Prairie State

Origin of name: Named for the French spelling of the French Catholic missionaries and explorer's name for the Illinois Native Americans.

Motto: “State sovereignty, national union”

Slogan: "Middle of Everything"

State symbols: 

Flower: Violet (1908)

Tree: White oak (1973)

Animal: White-tailed deer (1982)

Bird: Cardinal (1929)

Fish: Bluegill (1986)

Vegetables: Sweet corn (2015)

Song: “Illinois” (1925)

Fossil: Tully monster (1989)

Insect: Monarch butterfly (1975)

Dance: Square dance (1990)

Mineral: Fluorite (1965)

Horse: Thoroughbred horse (2006)

Reptile: Painted turtle (2006)

Rock: Dolostone (2022)


Governor: J. B. Pritzker (to Jan. 2027) 

Lieut. Governor: Juliana Stratton (to Jan. 2027)

Secy. of State: Alexi Giannoulias (to Jan. 2027)

General Treasurer: Mike Frerichs (to Jan. 2027)

Atty. General: Kwame Raoul (to Jan. 2027)

U.S. Representatives: 17

Senators: Dick Durbin, D (to Jan. 2027); Tammy Duckworth, D (to Jan. 2029)

Historical biographies of Congressional members

State website:


Residents: Illinoisan 

Resident population: 12,582,032 (6th Largest State, 202) 

10 largest cities (2023): Chicago, 2,608,425; Aurora, 177,108; Joliet, 150,718; Naperville, 148,754; Rockford, 145,754; Elgin, 112,504; Springfield, 111,711; Peoria, 109,447; Champaign, 90,522; Waukegan, 87,536.

Race/Ethnicity: White (60.0%); Hispanic or Latino (18%); Black or African American (14.7%); Asian (6.1%); Two or More Races (2.2%); American Indian or Alaska Native (0/6%); Native Hawaiian and Other Pacific Islander (0.1%)

Religion: Catholic (28%); Unaffiliated (22%); Evangelical Protestant (20%); Mainline Protestant (16%); Historically Black Protestant (7%); Jewish (2%); Muslim (1%); Hindu (1%); Buddhist (1%); Orthodox Christian (1%); Jehovah’s Witness (1%)

Sex: Male (49.9%); Female (50.1%)

Age: Under 18 (25.3%); 18-64 (56.1%); 65 and over (18.6%). Median Age: 38.3


GDP: 797.97 billion dollars (5th in the U.S., 2022) 

Unemployment: 4.2% (2022)


Land area: 57,915 sq mi. (149,997 sq km)

Geographic center: In Lincoln Co., 28 mi. NE of Springfield

Number of counties: 102

Largest county by population and area: Cook, 5,109,292 (2022); McLean, 1,183.38 sq mi. 

State parks/recreation areas: 182

See additional census data

Tourism office 


Illinois joined the Union on December 4, 1818, as the 21st state. It is bordered to the north by Wisconsin, Lake Michigan to the northeast, Indiana to the east, Kentucky to the southeast, Missouri to the west, and Iowa to the northwest. The capital is Springfield, in the west-central part of the state. The state’s area is 57,914 sq. miles (149,996 sq km).

The state of Illinois is characterized by the urban-rural divide between Cook County, where Chicago is located, and the remainder of the state. While Chicago is an industrial hub for the United States, the remainder of the state is largely rural and agricultural. Politically, Illinois tends to be a swing state as the population changes.

Illinois Geography

Illinois is located in the Midwest region of the United States and the Great Lakes region of North America. Illinois is bordered to the north by Wisconsin, Lake Michigan to the northeast, Indiana to the east, Kentucky to the southeast, Missouri to the west, and Iowa to the northwest. The state spans 385 from north to south.

Most of Illinois’s land is flat plains in the western, northern, and southern regions. The southernmost section of the state has gently sloping, rolling hills and includes the Shawnee National Forest. The northwestern section has rolling hills and includes the state’s highest point, Charles Mound (1,235 feet, 376 m). 

Northern and central Illinois have fertile, deep, black soil, which makes agriculture very successful, while the soil to the south is less suited for farming. 

More than 900 streams drain into the Mississippi River. The Chicago and Calumet Rivers have had their flow changed through canals to drain into the Mississippi via the Illinois River. The Ohio River joins the Mississippi River at the state’s southern tip. Chicago and its suburbs draw water from Lake Michigan, while the remainder of the state draws water from underground reservoirs. 

The climate of Illinois varies regionally in both temperature and precipitation. The state experiences cold, snowy winters and hot summers. Winters are most extreme in northern Illinois, around Lake Michigan. Precipitation is about 34 inches (864 mm) in the north and 46 inches (1,170 mm) in the south.

Illinois has two vegetation regions: the tallgrass prairie of northern and central Illinois and the oak-hickory forest of the western and southern parts of the state. While most of the prairies were previously destroyed, some sites have been restored. Midewin National Tallgrass Prairie is the largest restored prairie in the state. Only 6,200 square miles (16,000 square km) of forest remain in Illinois. Wildflowers and a variety of trees, such as white pines, tamaracks, and cypress trees, can be found throughout the state. 

Illinois is home to a large variety of animal life, including several species of forest rodents, bats, foxes, and rabbits. Bobcats, coyotes, bears, and deer can also be found in Illinois. A large variety of birds, including many species of geese, ducks, sandpipers, and gulls, inhabit the state. 

Illinois People and Population

According to the U.S. Census Bureau estimates for 2022, Illinois has a population of 12,582,032, making it the sixth most populous state in the United States. Chicago is the largest city with a population of 2,608,425. Illinois residents are called Illinoisians.

Demographically, the population of Illinois is predominantly white (60.0%), followed by Hispanic or Latino (18.0%), Black or African American (14.7%), and Asian (6.1%). Other ethnicities, including Native Americans, Pacific Islanders, and various multiracial groups make up a small percentage of the population.

The state also has a sizable population of senior citizens, with those aged 65 and over making up 18.6% of the population. The median age of the population is approximately 38 years old.

Catholicism is the most prevalent religion (28%), followed by Evangelical Protestant (20%) and Mainline Protestant (16%). Historically Black Protestants, Jews, and Muslims round out the religions. There is a significant percentage of the population who identify as unaffiliated or non-religious (20%).

Historically, Illinois was predominately white, with immigrants coming from Germany, Russia, Ireland, and other European countries. Slaves were first brought to the state in 1719, but numbers remained low until the American Civil War. The number of African Americans steadily increased until World War I and the Great Migration brought a steady flow of African Americans to major industrial centers in the north. Today, most African Americans in Illinois live in Chicago and Cook County. The Hispanic population has also steadily grown in recent decades. 

Illinois Government

The state government of Illinois operates under a framework outlined in its constitution, which establishes the three branches of government: executive, legislative, and judicial. The top officials in the state government include the Governor, Lieutenant Governor, Attorney General, Secretary of State, Comptroller, and Treasurer. 

The executive branch is split into several statewide offices, with the governor acting as chief executive. J. B. Pritzker has been the governor since 2019. Juliana Stratton is the lieutenant governor, Jesse White is the Secretary of State, and Kwame Raoul is the Attorney General. 

The Illinois General Assembly is the state legislature and is a bicameral body. There are 118 members of the House of Representatives and 59 members of the Senate, both of which have Democratic majorities. Representatives serve two-year terms while Senators serve two four-year terms and one two-year term in a decade. The Illinois Compiled Statutes are the codified statutes that constitute the general state laws. 

The General Assembly is responsible for passing a state budget before the governor approves or vetoes the proposal. According to the Illinois Office of Management and Budget, in 2023, Gov. J.B. Pritzker signed a $50.428 billion budget for the 2024 fiscal year. This budget is set against projected revenues of $50.611 billion, providing a $183 million surplus.

The Judiciary of Illinois is the court system in the state. The Supreme Court oversees the administration of the Appellate and Circuit Courts. 

The Illinois government includes a variety of state agencies, including: 

  • Illinois Department of Revenue

  • Guardianship and Advocacy Commission

  • Illinois Department of Agriculture

  • Energy Management Agency

  • Illinois Department of Correction

Administrative divisions of Illinois are counties, townships, precincts, cities, towns, villages, and special-purpose districts. Eighty-five of the 102 counties are divided into townships and precincts. Illinois has more units of local government than any other state, at over 8,000. 

Local governments are responsible for providing a variety of services. Property taxes are a major source of tax revenue. 

As of July 2022, there were 852 public school districts in Illinois. The State Board of Education divides the state into 60 educational regions. The State Board of Education was established in 1975, changing oversight from an elected superintendent to a board of appointed citizens.  Approximately 89.9% of high school students graduated in 2021. The Illinois Board of Higher Education oversees all higher education in the state. There are a variety of public and private colleges and universities in the state including the University of Chicago, Northwestern University, and the University of Illinois.

In national elections, Illinois has leaned Democratic, having consistently voted for Democratic presidential candidates since the 1990s. Chicago and Cook County are Democrat Party strongholds in the state, with most of the rural areas voting Republican. 

Illinois Economy

Illinois has a diverse economy, including manufacturing, agriculture, finance, mining, transportation, government, and technology. In 2022, Illinois had the fifth largest economy in the United States, bringing in about $797.97 billion. 

Farmlands cover about 75% of the state’s land and, as of 2019, there were about 72,000 farms. While the number of farms has reduced by more than half since 1950, farm sizes have doubled due to increased technology. Illinois typically ranks among the top producers of soybeans and corn. The state is also known for its pork and dairy products. Most farms in the state are family-owned.

Illinois consistently ranked high in the manufacture of food products, chemicals, fabricated metals, computing, and electronic products, as well as printing and publishing establishments. It also produces a large amount of nonelectrical machinery. The largest concentration of manufacturing plants is in the Chicago metropolitan area. Ford Motor Co., Chicago Assembly Plant, Medline Industries Inc., FCA US LLC, and AbbVie Inc. are the top manufacturing employers.

Chicago is home to O’Hare International Airport, one of the largest airports in the United States, and freight and passenger rail networks. Additionally, Chicago is one of the principal hubs for the national road system. The Port of Chicago was expanded with the completion of the St. Lawrence Seaway in 1959. Lake Michigan is connected to the Mississippi River via the Illinois and Michigan Canals.

Illinois Interesting Facts

As the state’s largest city and metropolitan area, Chicago monopolizes the cultural influence of the state of Illinois. Illinois is also called the “Land of Presidents” because it is the birthplace of eight U.S. presidents. Illinois is also known as the birthplace of Route 66, the iconic American highway. 

Chicago: The Windy City

Chicago is an economic and cultural powerhouse in the United States. Home to the Art Institute of Chicago, the John G. Shedd Aquarium, and the Field Museum of Natural History, the city holds incredible collections. The Chicago Symphony Orchestra and Opera are world-renowned. Poor Black people who migrated from the South to northern cities during the Great Migration brought jazz music with them. In Chicago, Chicago blues and “Chicago Style” Dixieland jazz developed in the city. Famous artists who were born in Chicago include Nat King Cole, Muddy Waters, and Bud Freeman. 

Deep-dish pizza was developed in Chicago and is one of the must-eats when visiting the city. The Chicago-style hot dog, which is a beef hotdog on a poppy seed bun topped with yellow mustard, green relish, chopped onions, tomato slices, a pickle spark, sport peppers, and celery salt, is a local favorite. 

The city is home to several professional sports teams, including baseball teams the Chicago Cubs and the Chicago White Sox, a football team the Chicago Bears, a basketball team the Chicago Bulls, and a hockey team the Chicago Blackhawks. 

The Land of Presidents

Illinois is the home or birthplace of four United States presidents: Abraham Lincoln, Ulysses S. Grant, Ronald Reagan, and Barack Obama. While Ronald Reagan was the only one of the four who was born in the state, each man lived or served in the state government. 

The Lincoln Home National Historic Site is located in Springfield. Added to the National Register of Historic Places in 1966, this protected site was the only home that Abraham Lincoln and his wife, Mary Todd Lincoln, ever owned. The Ulysses S. Grant Home in Galena in far northwestern Illinois is another protected historic site. The Ronald Reagan Boyhood in Dixon is also protected. 

Barack Obama served in the Illinois Senate from 1997–2002 and as the United States Senator from 2005–2008 before being elected to the office of president.

Route 66

The iconic American Highway was built in 1926 and ran from Chicago to Santa Monica, California. A symbol of loss, escape, and hope for a new beginning, the road played a significant role in American culture throughout most of the 20th century. Migrants fleeing the Dust Bowl traveled west on the highway. 

Businesses that were established along the highway grew during the heyday of the highway. While the highway had several decades of significance, in 1956 when President Dwight Eisenhower signed the Interstate Highway Act, the infrastructure and importance of Route 66 began to decline. The highway was decommissioned in 1985, but restoration activities began soon after. While it is impossible to drive along Route 66 from Chicago to California, sections of the highway still exist in several states or have been restored as an homage to the highway’s history. 

Illinois History

People have inhabited the land that is present-day Illinois for thousands of years. Shaped by shifting European occupation throughout the 16 and 1700s, Illinois’s history is dominated by European and American colonization. With an early anti-slavery sentiment, Illinois was the first state to outlaw slavery. The dichotomy between the state’s agricultural values and industrial importance shifts and moves the state’s values through modern times.

Pre-Colonial History

People have inhabited the land of Illinois since 8,000 B.C. Before European exploration and settlement, the Cahokia, Illinois, Ottawa, and Potawatomi tribes lived there. One of the most remarkable achievements of the prehistoric peoples in Illinois was the establishment of the Cahokia Mounds. The Cahokia civilization, centered around present-day Collinsville, Illinois, flourished between the 9th and 14th centuries. The Cahokia Mounds consisted of earthen mounds, including Monk's Mound, the largest prehistoric earthwork in the Americas. These mounds served as ceremonial and cultural centers for the Cahokia people and represented their advanced social and religious practices.

The indigenous peoples of Illinois practiced agriculture, cultivating crops such as maize, beans, and squash. They also engaged in hunting, fishing, and gathering. The Native American communities developed complex trade networks across vast distances.

Colonial History

In the late 17th century, French explorers Louis Jolliet and Jacques Marquette became the first European explorers to visit Illinois in 1763. René-Robert Cavelier, Sieur de La Salle established Fort Crèvecoeur. They established fur trading posts in the region, forming alliances with some Native American tribes.

France formally claimed the territory of Illinois as part of New France. However, following the French and Indian War (1754–1763), the area came under British control through the Treaty of Paris. The British Empire sought to consolidate its holdings and enforce its authority over the newly acquired territories.

During the American Revolution, in 1778, the American forces captured Kaskaskia, a stronghold of the British government in the region. Illinois was part of the Northwest Territory after the American Revolution until its division in 1800, when Illinois became part of the Indiana Territory. The Illinois Territory was formed in 1809. Slavery was technically legal in the territory, but it was not widespread due to the region's agricultural composition and the lack of reliance on plantation-based economies. When Illinois gained statehood in 1818, it entered the Union as a free state, making it one of the first states to prohibit slavery within its borders.

Pre-Civil War History

Early in Illinois’s history, the majority of the population lived on the eastern and western edges of southern Illinois. Residents here were primarily engaged in fur trading. In 1848, with the completion of the Illinois and Michigan Canals, the population of Illinois began to increase, and the economy boomed. Chicago emerged as a major transportation hub, fueled by its strategic location and access to waterways.

Although slaves were present in the state, residents rejected a constitutional convention whose implied purpose was to legalize slavery. As more people from the East moved into Illinois during the 1830s and 1840s, the pro-slavery sentiment decreased. Like most northern states at the time, oppressive laws still limited African American rights

Illinois remained loyal to the Union when the Civil War began. Illinois sent more than 250,000 troops to serve in the Union Army. Cairo, a town at the southern tip of the state at the confluence of the Mississippi and Ohio Rivers, served as a strategic base for training and supplying troops. General Ulysses S. Grant and Admiral Foote had headquarters in Cairo. 

Post-Civil War History 

Following the Civil War, Illinois experienced rapid industrialization and urbanization, especially in Chicago. The state's manufacturing sector grew, attracting workers from rural areas and immigrants from Europe. Industries such as steel, coal mining, meatpacking, and machinery manufacturing thrived. Thanks to its access to transportation networks and its position as a major financial and trading hub, Chicago became a center of commerce and industry. 

Labor movements and worker activism were significant during this period, with notable events such as the Haymarket Affair in 1886 and the Pullman Strike in 1894. These events had a lasting impact on labor rights and the development of the American labor movement. From Sunday, October 8, 1871, through Tuesday, October 10, 1871, the Great Chicago Fire burned four square miles of the city. 

At the turn of the century, Illinois’s population was nearly 5 million. Immigration from Europe and the migration of African Americans from the South fueled the state’s growth. In 1937, oil strikes in Marion and Crawford counties led to the state becoming the nation's fifth-ranking producer of oil. 

In the 1920s and 1930s, with the prohibition of alcohol, Chicago became a hotspot for bootlegging and mobster violence. Most notoriously, Al Capone led one of the most feared gangs in the city. Capone took over control of “the Outfit” in the mid-1920s and led the gang to become the most powerful in the city. In 1929, mob violence garnered national attention with the Valentine’s Day Massacre.

During World War II, Illinois manufactured 6.1% of the United States’s armaments. In 1942, the University of Chicago conducted the first nuclear chain reaction as part of the Manhattan Project. 

Modern History

Since World War II, Illinois has continued to experience significant population and economic growth. With the activation of the first experimental nuclear power-generating system in 1957, Illinois began its path to leading the nation in nuclear production. 

Politically, Illinois is divided between the Democratic stronghold of Chicago and Cook County and the Republican central region of the state. Southern Illinois tends to change parties. The state has a reputation for political corruption and fraud. Many state officials have served prison time, and four governors from the late 20th century through the 21st have been convicted of federal felonies. Former governors Otto Kerner, Daniel Walker, George Ryan, and Rod Blagojevich have all been indicted on a variety of charges, including corruption, bribery, fraud, and tax evasion.

Illinois recognized civil unions in 2011 and legalized cannabis in 2020. In 2017, Governor Bruce Rauner signed a bill that prohibited state and local law enforcement officers from arresting anyone solely because of their immigration status. On March 9, 2020, Governor J.B. Pritzker implemented a state of emergency due to the COVID-19 pandemic. The state of emergency ended in May 2023. 

People Also Ask…

That’s everything you need to know about the state of Illinois, but how well do you know the other U.S. states? For the ultimate test, try out this challenge in which you have to guess the state based only on its geographic outline with Infoplease's State Outlines Quiz.

What Is Illinois Best Known For?

Illinois is known for its early abolition of slavery, economic importance, and the city of Chicago. Additionally, the state is home to the first McDonald’s, marks the beginning of the world-famous Route 66, and is home to several unique foods, including deep-dish pizza, Chicago-style hotdogs, Italian beef sandwiches, and chicken vesuvio.

Is Illinois a Good Place To Live?

The U.S. World and News Report list of best states to live in for 2023 rated Illinois as the 36th best state to live in. While the state’s economy is strong, many people are leaving the state, especially in Chicago and Cook County. Harsh winters, high crime in some areas, and a high tax burden are causes for people leaving. 

What is the sales and use tax in Illinois?

Illinois’s sales and use tax rate is 6.25% on most goods and 1% on qualifying food, drugs, and medical equipment. Taxes may vary from place to place because local jurisdictions can levy their own taxes, which are added to the state sales and use tax.

See more on Illinois:
Encyclopedia: Illinois
Encyclopedia: Geography
Encyclopedia: Economy
Encyclopedia: Government
Encyclopedia: History
Monthly Temperature Extremes

Selected famous natives and residents:

The 50 States of America | U.S. State Information
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