The Great Chicago Fire

Lore & Background

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 spreading quickly. The fire leapt the south branch of the Chicago River and destroyed much of central Chicago and then crossed the main stem of the river, consuming the Near North Side.

Help flowed to the city 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.

Common Misconceptions (Editorial)

1. Many people think the Great Chicago Fire was officially blamed on Mrs. O'Leary's cow. In fact, the city never determined the cause, with the cow tale being only one unproven story among others, such as gamblers knocking over a lantern.
2. It is commonly believed the fire spread solely due to wooden buildings. While wood construction was a major factor, a long drought (only 1 inch of rain from July 4 to October 9) and strong southwest winds were crucial, as was an error by watchman Mathias Schaffer, who sent firefighters to the wrong location.

Why It Matters (Editorial)

The Great Chicago Fire endures as a cautionary tale about urban planning and infrastructure vulnerability—a single spark, compounded by drought, wooden construction, and human error, leveled a major American city. Its legacy reminds us how quickly a city's resilience can be overwhelmed when natural conditions and systemic oversights converge, a lesson that remains relevant as modern cities face their own fire and climate risks.

Reader's Guide

According to Nancy Connolly, great-great-granddaughter of Catherine O'Leary, the fire is said to have started at about 8:30 p.m. on October 8, in or around a small barn belonging to the O'Leary family that bordered the alley behind 137 W. DeKoven Street when Daniel 'Peg-Leg' Sullivan accidentally knocked over a lantern while looking for beer for a party. The shed next to the barn was the first building to be consumed by the fire. City officials never determined the cause of the blaze, but the rapid spread of the fire due to a long drought in that year's summer, strong winds from the southwest, and the rapid destruction of the water pumping system explain the extensive damage of the mainly wooden city structures.

There has been much speculation over the years on the single start to the fire. The most historically popular tale blames Mrs. O'Leary's cow, which allegedly knocked over a lantern; others state that a group of men were gambling inside the barn and knocked over a lantern. Still other speculation suggests that the blaze was related to other fires in the Midwest that day.

In 1997, the Chicago City Council formally exonerated O'Leary of any responsibility for the fire, following research by historian Richard Bales. The fire's spread was aided by the city's use of wood as the predominant building material in a style called balloon frame. More than two-thirds of the structures in Chicago at the time of the fire were made entirely of wood, with most of the houses and buildings being topped with highly combustible tar or shingle roofs. All of the city's sidewalks and many roads were also made of wood.

Compounding this problem, Chicago received only 1 inch (25 mm) of rain from July 4 to October 9, causing severe drought conditions before the fire, while strong southwest winds helped to carry flying embers toward the heart of the city. In 1871, the Chicago Fire Department had 185 firefighters with just 17 horse-drawn steam pumpers to protect the entire city. The initial response by the fire department was timely, but due to an error by the watchman, Mathias Schaffer, the firefighters were initially sent to the wrong place, allowing the fire to grow unchecked.