The Great Chicago Fire was a conflagration

Conflagration

A conflagration or a blaze is an uncontrolled burning that threatens human life, health, or property. A conflagration can be accidentally begun, naturally caused , or intentionally created . Arson can be accomplished for the purpose of sabotage or diversion, and also can be the consequence of...

 that burned from Sunday, October 8, to early Tuesday, October 10, 1871, killing hundreds and destroying about 4 square miles (10 km²) in Chicago

Chicago

Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

, Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

. Though the fire was one of the largest U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 disasters of the 19th century, the rebuilding that began almost immediately spurred Chicago's development into one of the most populous and economically important American cities.

On the municipal flag of Chicago

Municipal Flag of Chicago

The municipal flag of Chicago consists of two blue horizontal stripes on a field of white, each stripe one-sixth the height of the full flag, and placed slightly less than one-sixth of the way from the top or bottom, respectively. Between the two blue stripes are four red, six-pointed stars...

, the second star commemorates the fire.