The Great Chicago Fire was a conflagration that burned in the American city of Chicago during October 8–10, 1871. The fire killed approximately 300 people, destroyed roughly 3.3 square miles (9 km2) of the city including over 17,000 structures, and left more than 100,000 residents homeless. The fire began in a neighborhood southwest of the city center. A long period of hot dry windy conditions, and the wooden construction prevalent in the city, led to the conflagration. The fire leapt the south branch of the Chicago River and destroyed much of central Chicago and then leapt the main branch of the river, consuming the Near North Side.

Help flowed to the city from near and far after the fire. The city government improved building codes to stop the rapid spread of future fires and rebuilt rapidly to those higher standards. A donation from the United Kingdom spurred the establishment of the Chicago Public Library, a free public library system, a contrast to the private, fee-for-membership libraries common before the fire.