Mrs. O’Leary’s Cow
The causes of the massive blaze, which destroyed much of Chicago in October 1871, were perilous conditions: a long drought during a very hot summer, and the fact that the city had been built almost entirely of wood.
Within a few days of the fire, a Chicago Republic reporter named Michael Ahern wrote an article including the rumor about Mrs. O’Leary’s cow kicking over a kerosene lantern, igniting hay in the barn and starting the fire. The story took hold. In 1893, Ahern admitted that he created this fiction for colorful copy. Nonetheless, the story persists today.
Although no one disputes that a fire started in Mrs. O’Leary’s barn at 9:00pm on October 8, 1871, whether or not the cow started the blaze is a 140-year-old debate. chicagohistory.org