The U.S. Census Bureau defines the 13 western-most states as the Western United States. The most populous metropolitan area in the western United States is the Los Angeles metropolitan area. The western United States is home to an estimated 30,000 mountain lions.
There is no consensus on the definition of what states constitute the western United States. The U.S. Census Bureau's definition divides the region into two areas, the Pacific and Mountain divisions. The Los Angeles metropolitan area is the second largest in the United States and 18th largest in the world. As of 2013, the population of the Los Angeles metro area is 13,131,431.