1818    Illinois became 21st state

1818    Illinois becomes the 21st U.S. state.

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.

1894    Pullman Strike: Four thousand Pullman Palace Car Company workers go on a wildcat strike in Illinois.

1925    The Tri-State Tornado hits the Midwestern states of Missouri, Illinois, and Indiana, killing 695 people.

1927    The University of Chicago's local collegiate organization, Phi Sigma, becomes incorporated under Illinois law as Eta Sigma Phi, the National Honorary Classical Fraternity.

1930    ''Chicago Tribune'' reporter Jake Lingle is killed during rush hour at the Illinois Central train station by the Leo Vincent Brothers, allegedly over a 100,000 USD gambling debt owed to Al Capone.

1933    The Century of Progress World's Fair opens in Chicago, Illinois.

1944    Franklin D. Roosevelt wins the Democratic Party nomination for the fourth and final time at the 1944 Democratic National Convention in Chicago, Illinois.

1955    McDonald's restaurant dates its founding to the opening of a franchised restaurant by Ray Kroc, in Des Plaines, Illinois

1990    The Lower Ohio Valley tornado outbreak spawns 66 confirmed tornadoes in Illinois, Indiana, Kentucky, and Ohio, killing 12. Petersburg, Indiana, is the hardest-hit town in the outbreak, with 6 deaths.

2003    Illinois Governor George Ryan commutes the death sentences of 167 prisoners on Illinois' death row based on the Jon Burge scandal.