Denver, the City and County of Denver, is Colorado's capital and most populous municipality. Denver is situated on the western side of the High Plains, in the South Platte River Valley just east of the Rocky Mountains Front Range. With an estimated 727,211 population, Denver is the 19th-populated city in the United States. It was one of the fastest-growing major cities in the US. The greater Denver metropolitan area comprises a majority of the Front Range region's population and economic development. Denver's economy is partially focused on its geographical location and its relation to some of the major transportation systems in the world. It has become a natural location for the storage and distribution of goods and services to the mountain states, to the southwest states and to all western countries.