Huntsville is the most populous city in the U.S. state of Alabama. The population was 215,006 at the 2020 census, making it the 100th-most populous city in the U.S., while the Huntsville metropolitan area has an estimated 542,000 residents and is the second-most populous metropolitan area in the state. As of July 1, 2025, the city's population was estimated to be 249,102 – a 15.9% increase since the 2020 Census. This makes it among the top 20 fastest growing cities in the US. Huntsville is the county seat of Madison County, with portions extending into Limestone County, Marshall County, and Morgan County.