Huntsville is a city located primarily in Madison County in the central part of the far northern region of the U.S. state of Alabama. Huntsville is the county seat of Madison County. The city extends west into neighboring Limestone County. Huntsville's population was 180,105 as of the 2010 U.S. Census. The Huntsville Metropolitan Area's population was 417,593. Huntsville is the fourth-largest city in Alabama and the largest city in the four-county Huntsville-Decatur Combined Statistical Area, which at the 2010 census had a total population of 571,422.