Notable as dividing lines in the city are the two branches of the Chicago River. In early days the river was important because the narrow watershed between it and the Des Plaines River (draining into the Mississippi through the Illinois River) offered an easy portage that led explorers, fur traders, and missionaries from the Great Lakes to the Great Plains. Father Marquette and Louis Jolliet arrived here in 1673, and the spot was well known for a century before Jean Baptiste Point Sable (or Point DuSable or Point de Sable), a black man possibly of Haitian origin, set up a trading post at the mouth of the river. John Kinzie, who succeeded him as a trader, is usually called the father of Chicago.
A military post, Fort Dearborn, was established in 1803. In the War of 1812 its garrison perished in one of the most famous tragedies of Western history. Fort Dearborn was rebuilt in 1816, and the construction of the Erie Canal in the next decade speeded the settling of the Midwest and the growth of Chicago. Harbor improvements, lake traffic, and the peopling of the prairie farmlands brought prosperity to the city. The Illinois and Michigan Canal, however, authorized by Congress in 1827 and completed in 1848, was soon rendered virtually obsolete by the arrival of railroads.
By 1860 a number of rail lines connected Chicago with the rest of the nation, and the city was launched on its career as the great midcontinental shipping center. Gurdon S. Hubbard had already contributed to the establishment of the meatpacking industry, with its large stockyards. In 1871 the shambling city built of wood was almost entirely destroyed by a great fire (according to legend started when Mrs. O'Leary's cow kicked over a lantern), which killed several hundred people, rendered 90,000 homeless, and destroyed some $200 million worth of property.
Chicago was rebuilt as a city of stone and steel. Industries sprang up, attracting thousands of immigrants. Many ethnic groups contributed to the modern city, including Germans, Scandinavians, Irish, Jews, Italians, Poles, Czechs, African Americans, Lithuanians, Croats, Greeks, and Chinese. With industry came labor strife, highlighted by the Haymarket Square riot of 1886 and the great strikes at Pullman in 1894 (see Debs, Eugene V., and Altgeld, John P.). Upton Sinclair's novel of the Chicago stockyards, The Jungle, aroused public indignation and led to investigations and improvements.
The city, although proud of its reputation for brawling lustiness, was also the center of Midwestern culture. Theodore Thomas and the Chicago Symphony Orchestra founded a great musical tradition. Chicago's literary reputation was established in the early 20th cent. by such men as Carl Sandburg, Theodore Dreiser, Eugene Field, Edgar Lee Masters, and James T. Farrell. Saul Bellow and Studs Terkel would continue this tradition later in the century.
Most notable in the development of American thought and taste in art was the World's Columbian Exposition of 1893. One of the architects at the fair was Louis H. Sullivan, who, together with D. H. Burnham, John W. Root, Dankmar Adler, Frank Lloyd Wright, and others, made Chicago a leading architectural center. In 1909, D. H. Burnham and Edward Bennett devised their Plan of Chicago, later known as the "Burnham Plan," a forward-looking piece of city planning containing many features that were implemented later. It was here that one of the distinctive U.S. contributions to architecture, the skyscraper, came into being. Chicago's continuing interest in this type of structure is seen in the John Hancock Center (1968), the Aon Center (1974, formerly the Amoco Building, earlier the Standard Oil Building), the Willis Tower (1974, formerly the Sears Tower), and the Trump International Hotel and Tower (2009).
Between World War I and 1933, Chicago earned unenviable renown as the home ground of gangsters—Al Capone being perhaps the most notorious—and its reputation for gangster warfare persisted long after that violent era had passed. Despite the worldwide depression of the 1930s, Chicago's world's fair, the Century of Progress Exposition (1933–34), proved how greatly the city had prospered and advanced. Perhaps the most significant event in World War II occurred (Dec. 2, 1942) under the stands of the Univ. of Chicago's Stagg Field, when Enrico Fermi and a group of scientists working on the government's atom bomb project achieved the world's first nuclear chain reaction. With the war came considerable growth in the Chicago metropolitan area, especially in outlying suburbs.
The city itself declined 23% in population between 1950 and 1990, although its diverse economic base spared it the worst of the economic decay of other large Midwestern cities. The population decline was reversed between 1990 and 2000, when it grew some 4%, largely due to the influx of Hispanic and Asian residents. Chicago's many cultural and other attractions make it a popular convention city; among the 25 national political conventions held there were the Republican national conventions of 1952 and 1960 and the Democratic national conventions of 1952, 1956, 1968, and 1996. The 1968 Democratic National Convention saw violent clashes between demonstrators and Chicago police and the National Guard. Mayor Richard J. Daley was criticized by the media for his manner of putting down the demonstrations, but Chicagoans overwhelmingly supported him. Chicagoans subsequently elected their first woman mayor (Jane Byrne, 1979–83) and their first African-American mayor (Harold Washington, 1983–87). Richard M. Daley was first elected to the office his father long held in 1989, and subsequently became the city's longest serving mayor. Rahm Emanuel was elected to succeed Daley in 2011.