Did Mrs. O'Leary's Cow Start the Great Chicago Fire?

The Facts Behind the Incendiary Legend

Lithograph depicting Mrs. O'Leary and her cow, of Chicago Fire fame.
Lithograph depicting Mrs. O'Leary and her cow. Chicago History Museum/Getty Images

Popular legend has long held that a cow being milked by Mrs. Catherine O'Leary kicked over a kerosene lantern, igniting a barn fire that spread into the Great Chicago Fire.The famous story appeared soon after colossal fire that consumed much of Chicago and has spread ever since. But was the cow really the culprit?


The real blame for the enormous fire, which began on October 8, 1871, lies with a combination of perilous conditions: a long drought over a very hot summer, loosely enforced fire codes, and a sprawling city built almost entirely of wood. Yet Mrs. O'Leary and her cow took the blame in the public mind. Let's learn a little more about Mrs. O'Leary, her family, and why the legend endures to the present day.

The O'Leary Family

The O'Leary family, who were immigrants from Ireland, lived at 137 De Koven Street in Chicago. Mrs. O'Leary had a small dairy business, and she routinely milked cows in a barn behind the family's cottage.

So, part of the legend seems to be true. A fire did begin in O'Leary's barn at about 9:00 pm on Sunday, October 8, 1871.Catherine O'Leary and her husband Patrick, a Civil War veteran, later swore that they had already retired for the night and were in bed when they heard neighbors calling out about the fire in the barn. By some accounts, a rumor about a cow kicking over a lantern began spreading almost as soon as the first fire company responded to the blaze.

However, another rumor in the neighborhood was that a boarder in the O'Leary house, Dennis "Peg Leg" Sullivan, had slipped into the barn to have a few drinks with some of his friends. During their revelry they started a fire in the barn's hay by smoking pipes.

It is also possible the fire ignited from an ember which blew from a nearby chimney. Many fires did start that was in the 1800s, though they didn't have the conditions to spread as quickly and widely as the fire that night in Chicago.

No one will ever know what really happened that night in the O'Leary barn. What isn't disputed is that a fire began there and the blaze quickly spread. Assisted by strong winds, the barn fire eventually turned into the Great Chicago Fire.

Within a few days a newspaper reporter, Michael Ahern, wrote an article which put the neighborhood rumor about Mrs. O'Leary's cow kicking over a kerosene lantern into print. The story took hold, and was circulated widely.

The Official Report

An official commission investigating the fire heard testimony about Mrs. O'Leary and her cow in November 1871. An article in the New York Times on November 29, 1871, was headlined "Mrs. O'Leary's Cow." 

The article described the testimony given by Catherine O'Leary before the Chicago Board of Police and Fire Commissioners. In her account, she and her husband had been asleep when two men came to their house to alert them that their barn was on fire.

Mrs. O'Leary's husband, Patrick, was also questioned. He testified that he did not know how the fire started as he had also been asleep until he heard the neighbors.

The commission concluded in its official report that Mrs. O'Leary had not been in the barn when the fire began. The report did not state a precise cause of the fire, but mentioned that a spark blown from a chimney of a nearby house on that windy night could have started the fire in the barn.

The O'Learys After the Fire

Despite being cleared in the official report, the O'Leary family became notorious. In a quirk of fate, their house has actually survived the fire, as the flames spread outward away from property. Yet, facing the stigma of the constant rumors, which had spread nationwide, they eventually moved from De Koven Street.

Mrs. O'Leary lived out the rest of her life as a virtual recluse, only leaving her residence to attend daily mass. When she died in 1895 she was described as "heartbroken" that she was always blamed for causing so much destruction.

Years after Mrs. O'Leary's death, Michael Ahern, the newspaper reporter who had first published the rumor, admitted that he and other reporters had made up the story. They believed it would hype the story, as if a fire that destroyed a major American city needed any extra sensationalism.

When Ahern died in 1927, a small item from the Associated Press datelined Chicago offered his corrected account:

"Michael Ahern, last surviving reporter of the famous Chicago fire of 1871, and who denied the authenticity of the story of Mrs. O'Leary's famous cow which was credited with kicking over a lamp in a barn and starting the fire, died here tonight.
"In 1921, Ahern, in writing an anniversary story of the fire said that he and two other reporters, John English and Jim Haynie, concocted the explanation of the cow starting the fire, and admitted that he afterward learned that spontaneous combustion of hay in the O'Leary barn probably was the cause. At the time of the fire Ahern was a police reporter for The Chicago Republican."

The Legend Lives On

While the story of Mrs. O'Leary and her cow isn't true, the legendary tale lives on. Lithographs of the scene were produced in the late 1800s. The legend of the cow and the lantern were the basis for popular songs over the years, and the story was even told in a major Hollywood movie produced in 1937, "In Old Chicago."

The MGM film, which was produced by Daryl F. Zanuck, provided a completely fictitious account of the O'Leary family and portrayed the story of the cow kicking over the lantern as the truth. And while "In Old Chicago" may have been completely wrong on the facts, the movie's popularity and the fact that it was nominated for an Academy Award for Best Picture helped perpetuate the legend of Mrs. O'Leary's cow.

The Great Chicago Fire is remembered as one of the major disasters of the 19th century, along with the eruption of Krakatoa or the Johnstown Flood. And it's also remembered, of course, as it seemed to have a distinctive character, Mrs. O'Leary's cow, at the center of it.

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Your Citation
McNamara, Robert. "Did Mrs. O'Leary's Cow Start the Great Chicago Fire?" ThoughtCo, Sep. 8, 2021, thoughtco.com/mrs-olearys-cow-great-chicago-fire-1774059. McNamara, Robert. (2021, September 8). Did Mrs. O'Leary's Cow Start the Great Chicago Fire? Retrieved from https://www.thoughtco.com/mrs-olearys-cow-great-chicago-fire-1774059 McNamara, Robert. "Did Mrs. O'Leary's Cow Start the Great Chicago Fire?" ThoughtCo. https://www.thoughtco.com/mrs-olearys-cow-great-chicago-fire-1774059 (accessed March 27, 2023).