Denver (/ ˈ d ɛ n v ər /), officially the City and County of Denver, is the capital and most populous municipality of the U.S. state of Colorado.Denver is located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains.With an estimated population of 716,492 in 2018, Denver is the 19th-most populous U.S. city, and with a 19 ...