Answer: 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, and left more than 100,000 residents homeless.[3] 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.
The fire is claimed 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 DeKoven Street.[4] The shed next to the barn was the first building to be consumed by the fire. City officials never determined the exact cause of the blaze,[5] 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 a single start to the fire. The most popular tale blames Mrs. O'Leary's cow, who allegedly knocked over a lantern; others state that a group of men were gambling inside the barn and knocked over a lantern.[6] Still other speculation suggests that the blaze was related to other fires in the Midwest that day.[1]
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 flammable tar or shingle roofs. All of the city's sidewalks and many roads were also made of wood.[6] 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.[1]:144
In 1871, the Chicago Fire Department had 185 firefighters with just 17 horse-drawn steam pumpers to protect the entire city.[1]:146 The initial response by the fire department was quick, but due to an error by the watchman, Matthias Schaffer, the firefighters were sent to the wrong place, allowing the fire to grow unchecked.[1]:146 An alarm sent from the area near the fire also failed to register at the courthouse where the fire watchmen were, while the firefighters were tired from having fought numerous small fires and one large fire in the week before.[7] These factors combined to turn a small barn fire into a conflagration.
When firefighters finally arrived at DeKoven Street, the fire had grown and spread to neighboring buildings and was progressing toward the central business district. Firefighters had hoped that the South Branch of the Chicago River and an area that had previously thoroughly burned would act as a natural firebreak.[1]:147 All along the river, however, were lumber yards, warehouses, and coal yards, and barges and numerous bridges across the river. As the fire grew, the southwest wind intensified and became superheated, causing structures to catch fire from the heat and from burning debris blown by the wind. Around midnight, flaming debris blew across the river and landed on roofs and the South Side Gas Works.[1]:148