www.hsvcity.com 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 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 in 2008 had a total population of 545,770. It grew across nearby hills and along the Tennessee River, adding textile mills, then munitions factories, NASA's Marshall Space Flight Center and the United States Army Aviation and Missile Command nearby at the Redstone Arsenal. The National Trust for Historic Preservation named Huntsville to its "America's Dozen Distinctive Destinations for 2010" list.