Illinois is a state in the Midwestern region of the United States. Of the fifty U.S. states, it has the fifth largest gross domestic product (GDP), the sixth largest population, and the 25th largest land area. Chicago is the state’s largest city and the fifth largest city in North America with the capital in Springfield, located in the center of the state; other major metropolitan areas include Metro East (of Greater St. Louis), Peoria and Rockford.
“Illinois” is the modern spelling for the early French Catholic missionaries and explorers’ name for the Illinois Native Americans, a name that was spelled in many different ways in the early records. American scholars previously thought the name Illinois meant ‘man’ or ‘men’ in the Miami-Illinois language, with the original iliniwek transformed via French into Illinois. This etymology is not supported by the Illinois language, as the word for “man” is ireniwa, and plural of “man” is ireniwaki.
The name Illiniwek has also been said to mean ‘tribe of superior men’, which is a false etymology. The name Illinois derives from the Miami-Illinois verb irenwe·wa ‘he speaks the regular way’. This was taken into the Ojibwe language, perhaps in the Ottawa dialect, and modified into ilinwe· (pluralized as ilinwe·k). The French borrowed these forms, spelling the /we/ ending as -ois, a transliteration of that sound in the French of that time. The current spelling form, Illinois, began to appear in the early 1670s, when French colonists had settled in the western area. The Illinois’s name for themselves, as attested in all three of the French missionary-period dictionaries of Illinois, was Inoka, of unknown meaning and unrelated to the other terms.
Illinois is located in the Midwest region of the United States and is one of the eight states in the Great Lakes region of North America (which also includes Ontario, Canada).
Illinois has a climate that varies widely throughout the year. Because of its nearly 400-mile distance between its northernmost and southernmost extremes, as well as its mid-continental situation, most of Illinois has a humid continental climate (Köppen climate classification Dfa), with hot, humid summers and cold winters. The southern part of the state, from about Carbondale southward, has a humid subtropical climate (Koppen Cfa), with more moderate winters.
Average yearly precipitation for Illinois varies from just over 48 in (1,219 mm) at the southern tip to around 35 in (889 mm) in the northern portion of the state. Normal annual snowfall exceeds 38 in (965 mm) in the Chicago area, while the southern portion of the state normally receives less than 14 in (356 mm). The all-time high temperature was 117 °F (47 °C), recorded on July 14, 1954, at East St. Louis, and the all-time low temperature was −38 °F (−39 °C), recorded on January 31, 2019, during the January 2019 North American cold wave at a weather station near Mount Carroll, and confirmed on March 5, 2019.
This followed the previous record of −36 °F (−38 °C) recorded on January 5, 1999, near Congerville. Prior to the Mount Carroll record, a temperature of −37 °F (−38 °C) was recorded on January 15, 2009, at Rochelle, but at a weather station not subjected to the same quality control as official records.
The United States Census Bureau found that the population of Illinois was 12,812,508 in the 2020 United States census, moving from the fifth-largest state to the sixth-largest state (losing out to Pennsylvania). Illinois’ population slightly declined in 2020 from the 2010 United States census by just over 18,000 residents and the overall population was quite higher than recent census estimates.
Illinois is the most populous state in the Midwest region. Chicago, the third-most populous city in the United States, is the center of the Chicago metropolitan area or Chicagoland, as this area is nicknamed. Although Chicagoland comprises only 9% of the land area of the state, it contains 65% of the state’s residents. The losses of population anticipated from the 2020 census results do not arise from the Chicago metro area; rather the declines are from the Downstate counties.
Chicago is the largest city in the state and the third-most populous city in the United States, with its 2010 population of 2,695,598. The U.S. Census Bureau currently lists seven other cities with populations of over 100,000 within Illinois. Based upon the U.S. Census Bureau’s official 2010 population: Aurora, a Chicago satellite town that eclipsed Rockford for the title of second-most populous city in Illinois; its 2010 population was 197,899. Rockford, at 152,871, is the third-largest city in the state, and is the largest city in the state not located within the Chicago suburbs. Joliet, located in metropolitan Chicago, is the fourth-largest city in the state, with a population of 147,433. Naperville, a suburb of Chicago, is fifth with 141,853. Naperville and Aurora share a boundary along Illinois Route 59. Springfield, the state’s capital, comes in as sixth-most populous with 117,352 residents. Peoria, which decades ago was the second-most populous city in the state, is seventh with 115,007. The eighth-largest and final city in the 100,000 club is Elgin, a northwest suburb of Chicago, with a 2010 population of 108,188.
The most populated city in the state south of Springfield is Belleville, with 44,478 people at the 2010 census. It is located in the Illinois portion of Greater St. Louis (often called the Metro-East area), which has a rapidly growing population of over 700,000.
Other major urban areas include the Champaign-Urbana Metropolitan Area, which has a combined population of almost 230,000 people, the Illinois portion of the Quad Cities area with about 215,000 people, and the Bloomington-Normal area with a combined population of over 165,000.
The official language of Illinois is English, although between 1923 and 1969, state law gave official status to “the American language”. Nearly 80% of people in Illinois speak English natively, and most of the rest speak it fluently as a second language. A number of dialects of American English are spoken, ranging from Inland Northern American English and African-American English around Chicago, to Midland American English in Central Illinois, to Southern American English in the far south.
Over 20% of Illinoians speak a language other than English at home, of which Spanish is by far the most widespread, at more than 12% of the total population. A sizeable number of Polish speakers is present in the Chicago Metropolitan Area. Illinois Country French has mostly gone extinct in Illinois, although it is still celebrated in the French Colonial Historic District.
Roman Catholics constitute the single largest religious denomination in Illinois; they are heavily concentrated in and around Chicago, and account for nearly 30% of the state’s population. However, taken together as a group, the various Protestant denominations comprise a greater percentage of the state’s population than do Catholics. In 2010 Catholics in Illinois numbered 3,648,907. The largest Protestant denominations were the United Methodist Church with 314,461, and the Southern Baptist Convention, with 283,519 members. Illinois has one of the largest concentrations of Missouri Synod Lutherans in the United States.
A significant number of adherents of other Abrahamic faiths can be found in Illinois. Largely concentrated in the Chicago metropolitan area, followers of the Muslim, Baháʼí, and Jewish religions all call the state home. Muslims constituted the largest non-Christian group, with 359,264 adherents. Illinois has the largest concentration of Muslims by state in the country, with 2,800 Muslims per 100,000 citizens. Chicago is also home to a very large population of Hindus, Sikhs, Jains, and Buddhists.
The dollar gross state product for Illinois was estimated to be US$909 billion in 2019. The state’s 2019 per capita gross state product was estimated to be around $72,000. As of February 2019, the unemployment rate in Illinois reached 4.2%. Illinois’s minimum wage will rise to $15 per hour by 2025, making it one of the highest in the nation.
Because of its central location and its proximity to the Rust Belt and Grain Belt, Illinois is a national crossroads for air, auto, rail, and truck traffic.
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