East St. Louis, also known as ESTL, is a city located in St. Clair County, Illinois, within the United States. It is situated in the Metro East region of Southern Illinois and lies directly across the Mississippi River from downtown St. Louis, Missouri, and the Gateway Arch National Park.
The city reached its peak population in 1950, when it was the fourth-largest city in Illinois with 82,366 residents. According to the 2020 census, the population has significantly declined to 18,469, which is less than one-quarter of its 1950 peak and represents a decrease of nearly one-third since 2010.