The Huntsville-Decatur-Albertville, AL Combined Statistical Area is the most populated sub-region of North Alabama, and is the second fastest growing region in the State of Alabama, with 679,743 living within the CSA. It is also currently the 70th largest CSA in the country.The CSA is situated along the Tennessee River, and is made up of two separate metropolitan areas (Decatur and Huntsville) that are usually referred to as one. The area also consists of one micropolitan area, Albertville.