1833 Chicago is founded.
1837 Chicago is incorporated as a city.
1871 Four major fires break out on the shores of Lake Michigan in Chicago, Peshtigo, Wisconsin, Holland, Michigan, and Manistee, Michigan including the Great Chicago Fire, and the much deadlier Peshtigo Fire.
1889 Hyde Park and several other Illinois townships vote to be annexed by Chicago, forming the largest United States city in area and second largest in population.
1890 Chicago is selected to host the Columbian Exposition
1891 The Wrigley Company is founded in Chicago, Illinois.
1892 Opening ceremonies for the World's Columbian Exposition are held in Chicago, though because construction was behind schedule, the exposition did not open until May 1, 1893.
1893 The World's Columbian Exposition opens in Chicago.
1894 The troops sent by Grover Cleveland to Chicago to end the Pullman Strike are recalled.
1895 The first American automobile race takes place over the 54 miles from Chicago's Jackson Park to Evanston, Illinois. Frank Duryea wins in approximately 10 hours.
1896 William Jennings Bryan delivers his Cross of Gold speech advocating bimetalism at the 1896 Democratic National Convention in Chicago.
1902 In Chicago, the American Automobile Association is established.
1903 A fire at the Iroquois Theater in Chicago, Illinois kills 600.
1919 The dirigible ''Wingfoot Air Express'' crashes into the Illinois Trust and Savings Building in Chicago, killing 12 people.
1920 The League of Women Voters is founded in Chicago, Illinois.
1920 During the U.S. Republican National Convention in Chicago, U.S. Republican Party leaders gathered in a room at the Blackstone Hotel to come to a consensus on their candidate for the U.S. presidential election, leading the Associated Press to first coin the political phrase "smoke-filled room".
1929 Saint Valentine's Day massacre: Seven people, six of them gangster rivals of Al Capone's gang, are murdered in Chicago, Illinois.
1933 In Miami, Florida, Giuseppe Zangara attempts to assassinate President-elect Franklin D. Roosevelt, but instead shoots Chicago, Illinois Mayor Anton J. Cermak, who dies of his wounds on March 6, 1933.
1933 The Century of Progress World's Fair opens in Chicago, Illinois.
1933 The first Major League Baseball All-Star Game is played in Chicago's Comiskey Park. The American League defeats the National League 4–2.
1934 Outside Chicago's Biograph Theater, "Public Enemy No. 1" John Dillinger is mortally wounded by FBI agents.
1935 The dust bowl heat wave reaches its peak, sending temperatures to 109°F (44°C) in Chicago and 104°F (40°C) in Milwaukee, Wisconsin.
1944 Franklin D. Roosevelt wins the Democratic Party nomination for the fourth and final time at the 1944 Democratic National Convention in Chicago, Illinois.
1954 The German U-Boat U-505 begins its move from a specially constructed dock to its final site at Chicago's Museum of Science and Industry.
1960 In Chicago, the first televised debate takes place between presidential candidates Richard M. Nixon and John F. Kennedy.
1968 Riots in Chicago, Illinois, during the Democratic National Convention.
1969 The Chicago Eight trial opens in Chicago.
1969 In Chicago, the United States National Guard is called in for crowd control as demonstrations continue in connection with the trial of the "Chicago Eight" that began on September 24.
1969 Black Panther Party members Fred Hampton and Mark Clark are shot and killed in their sleep during a raid by 14 Chicago police officers.
1973 The Sears Tower in Chicago is topped out as the world's tallest building.
1979 American Airlines Flight 191: In Chicago, a McDonnell Douglas DC-10 crashes during takeoff at O'Hare International Airport killing 271 on board and two people on the ground.
1979 The roof of the uncompleted Rosemont Horizon near Chicago, Illinois collapses, killing 5 workers and injuring 16.
1982 Cyanide-laced Tylenol kills six people in the Chicago area. Seven are killed in all.
1999 A brutal snowstorm smashes into the Midwestern United States, causing 14 inches (359 mm) of snow in Milwaukee, Wisconsin, and 19 inches (487 mm) in Chicago, where temperatures plunge to -13 °F (-25 °C); 68 deaths are reported
2003 The Harris Theater opens, commencing a renaissance in the Chicago performing arts community.
2004 Millennium Park, considered Chicago's first and most ambitious early 21st century architectural project, is opened to the public by Mayor Richard M. Daley.
2008 The Trump International Hotel and Tower in Chicago is topped off at {{convert|1389|ft|m}}, at the time becoming the world's highest residence above ground-level.