The first Sears retail store opened in Chicago.
Source
The world's first self-sustaining nuclear chain reaction happened in Chicago Pile-1 at the University of Chicago. It was overseen by Enrico Fermi.
An F5 max rating tornado smashed through Plainfield, Illinois, killing 29 people, injuring 353, and causing $165 million in damages.
The sweeping machine (vacuum cleaner) was patented in Chicago, US, by Ives W. McGaffey.
Great Chicago Fire begins.
Illinois became the first US state to make it compulsory by law to wear a seatbelt.
