Bloomington is a city in McLean County, Illinois, United States, and its county seat. The 2020 census showed the city had a population of 78,680, making it the 13th-most populous city in Illinois and the fifth-most populous outside the Chicago metropolitan area. It is adjacent to the town of Normal, and is the more populous of the two principal municipalities of the Bloomington–Normal metropolitan area, which has a population of roughly 170,000.

Bloomington is 135 miles (217 km) southwest of Chicago and 162 miles (261 km) northeast of St. Louis. Bloomington is home to Illinois Wesleyan University and the headquarters for State Farm and Country Financial. Bloomington is also home to the minor league hockey team Bloomington Bison.

The Bloomington area was at the edge of a large grove occupied by the Kickapoo people before the first Euro-American settlers arrived in the early 1820s. Springing from the settlement of Keg Grove, later called Blooming Grove, Bloomington was named as county seat on December 25, 1830, when McLean County was created.

When the County of McLean was incorporated, a county seat was established, but the legislation stated the site of Bloomington "would be located later." Gavin Quinn, one of the new county's promoters, offered to donate 60 acres (240,000 m²) of his land for the new town. His offer was accepted, and Bloomington was laid out. Its lots were sold at a well-attended and noisy auction on July 4, 1831. At this time there were few roads, but rich soils brought new farmers who began commerce by conducting their business in the county. People came from all over to trade and do business at the town's center, known today as Downtown Bloomington, including Abraham Lincoln, who worked as a lawyer in nearby Springfield. Prominent Bloomington resident Jesse W. Fell, who founded the Bloomington Pantagraph and was most prominent in local real estate, had suggested the Lincoln-Douglas debates in 1854 and played a prominent role in pushing Lincoln to run for president.

In 1900, an officer on patrol discovered a fire in a laundry across the street from the old city hall and police station. He sounded an alarm but the fire destroyed most of the downtown, especially the areas north and east of the courthouse. The burnt area was quickly rebuilt from the designs of local architects George Miller and Paul O. Moratz.

Bloomington continued to grow during the first two decades of the 20th century. Agriculture, the construction of highways and railroads, and the growth of the insurance business all influenced the growth of Bloomington and its downtown. Most notably, State Farm was founded in June 1922 by retired farmer George J. Mecherle as a mutual automobile insurance company specializing in insurance for farmers.

The 1917 Bloomington Streetcar Strike was a labor dispute starting on May 28, 1917, when Amalgamated Transit Union Local 752 called a strike for union recognition, increased pay, and a shortened workday. It ended in July when the mayor of Bloomington, E.E. Jones, mediated contract talks between the workers and company from July 6 to 9. During this, the Illinois National Guard had been stationed outside the courthouse where mediation was occurring, equipped with machine gun emplacements.

In 1997, Judy Markowitz was elected as the city's first female and Jewish mayor. During her two terms as mayor, an arena was built in downtown Bloomington and the city's performing arts center began restoration. Bloomington also approved a gay rights ordinance in 2002. In 2021, Mboka Mwilambwe was elected as the city's first black mayor.