Chicago is the third-most populous city of the United States and the most populous city in the state of Illinois, positioned along Lake Michigan. The city's name comes from the Native American word Shikaakwa, which refers to a type of wild onion commonly called a "ramp". The US Army founded Fort Dearborn in the Chicago area in 1803 and organized the town of Chicago on 12 August 1833. In 1837, Chicago was incorporated as a city following the expulsion of the Potawatomi tribe, and it was the world's fastest growing city for decades.
During the 1850s and 1860s, the city was raised on jackscrews, accomodating rapid population growth and sanitation issues; however, the untreated sewage and industrial waste flowed into Lake Michigan, the city's primary freshwater source. In 1871, a great fire destroyed 3.3 miles of the city, killed 300 people, and made 100,000 people homeless, and the city was rebuilt with steel buildings; the world's first skyscraper, the Home Insurance Building, was built in 1885 with a steel skeleton. Chicago rapidly grew as hundreds of thousands of immigrants arrived, with Germans, Irish, Poles, Swedes, and Czechs making up nearly two-thirds of the city's foreign-born population; in 1900, 77% of Chicagoans were either foreign-born or children of immigrants. The Great Migration led to many African-Americans moving into the city, leading to racial tensions and violence. From 1919 to 1933, the city was a battleground for Prohibition bootleggers such as Johnny Torrio, Al Capone, Dean O'Banion, Bugs Moran, and Tony Accardo as they battled law enforcement and each other to control the illegal liquor trade. During the 1960s, white flight occurred, and the city became poorer and more violent. In 1968, there was fighting between protesters and police outside the Democratic Party's National Convention hall during the Vietnam War. In the following decades, "the Windy City" became known for its high crime rate, and President Donald Trump threatened to send in the US National Guard in 2016.
Chicago had a population of 2,695,598 in 2010, with its combined statistical area having a population of 9,882,634 people. 32.9% was African-American, 31.7% were white, 28.9% were Hispanic, and 5.5% were Asian, and 71% of Chicagoans are Christians, 22% irreligious, and 7% other faiths.