Eleven unincorporated towns governed by the Clark County government are part of the Las Vegas Township and constitute the largest community in the state of Nevada. The Valley is home to the three largest incorporated cities in Nevada: Las Vegas, Henderson and North Las Vegas. The Valley is largely defined by the Las Vegas Valley landform, a 600 sq mi (1,600 km 2) basin area surrounded by mountains to the north, south, east and west of the metropolitan area. The state's largest urban agglomeration, the Las Vegas Metropolitan Statistical Area is coextensive since 2003 with Clark County, Nevada. state of Nevada, and the second largest in the Southwestern United States. The Las Vegas Valley is a major metropolitan area in the southern part of the U.S.