Lubbock is an American city in the state of Texas. Located in the northwestern part of the state, a region known historically as the Llano Estacado, it is the county seat of Lubbock County, and the home of Texas Tech University. According to the 2000 U.S. Census, the city population was 199,564, making it the 90th largest city in the United States and the 11th largest in Texas. The 2006 population was estimated to be 212,169. Lubbock County had an estimated 2006 population of 254,862. Lubbock's nickname is the "Hub City" which derives from being the economic, education, and health care hub of a multi-county region commonly called the South Plains. The area is the largest contiguous cotton-growing region in the world and is heavily dependent on irrigation water drawn from the Ogallala Aquifer.