The 1896 St. Louis–East St. Louis tornado was a historic tornado that caused severe damage to downtown St. Louis, Missouri, East St. Louis, Illinois, and surrounding areas on Wednesday, May 27, 1896, at around 5:00 pm. One of the deadliest and most destructive tornadoes in U.S. history, this tornado was the most notable of a major tornado outbreak across the central United States which produced several other large, long-track, violent tornadoes and continued across the eastern United States the following day. The St. Louis tornado killed at least 255 people, injured over a thousand others, and caused more than $10 million in damage in about 20 minutes. More than 5,000 people were left homeless and lost all of their possessions. The hardest-hit areas of the city were the fashionable Lafayette Square and Compton Heights neighborhoods, as well as the poorer Mill Creek Valley. It remains the third-deadliest tornado in United States history.

East St. Louis is a city in St. Clair County, Illinois, United States. It is directly across the Mississippi River from downtown St. Louis, Missouri, and the Gateway Arch National Park. East St. Louis is in the Metro East region of Southern Illinois. Once a bustling industrial center, like many cities in the Rust Belt, East St. Louis was severely affected by the loss of jobs due to the flight of the population to the suburbs during the riots of the late 1960s. In 1950, East St. Louis was the fourth-largest city in Illinois when its population peaked at 82,366. As of the 2020 census, the city had a population of 18,469, less than one-quarter of the 1950 census and a decline of almost one third since 2010.