The City and County of Denver is the capital and largest city of the U.S. state of Colorado. It is located on the plains just east of the Rocky Mountains and forms the heart of the Denver-Aurora metropolitan area. The central downtown district is on the east side of the South Platte River, near its confluence with Cherry Creek, approximately fifteen miles from the foothills.Denver is the county seat of, and shares the same borders with, Denver County — one of the few consolidated city-counties in the United States. According to 2004 Census estimates , the city has a population of 556,835 and ranks as the 25th-largest in the United States and the sixth-largest state capital. The Denver Regional Council of Governments estimated that the 2005 population of the city was 579,744 (unofficial). The population of the Denver-Aurora metropolitan area was about 2,330,146, making it the twenty second-largest metropolitan area in the U.S. . The city claims to have the tenth largest downtown in the United States .Denver is nicknamed "The Mile-High City" because its official elevation, measured on the fifteenth step of the state capitol building's west side, is one statute mile (5,280 feet or 1,609 meters) above sea level. Also, a row of seats in the upper deck of Coors Field, home of Major League Baseball's Colorado Rockies (NL), is marked in purple (one of the team's colors) to indicate that the row is one mile above sea level. The city's elevation, as surveyed at Denver International Airport, is 5,431 ft (1,655 m).Denver has also been known historically as the Queen City of the Plains because of its important role in the agricultural industry of the plains regions along the foothills of the Front Range. Several US Navy ships have been named USS Denver in honor of the city.