 The Colorado Territory was created on February 28 , 1861 , Arapahoe County was formed on November 1 , 1861 , and Denver City was incorporated on November 7 , 1861 . Denver City served as the Arapahoe County Seat from 1861 until consolidation in 1902 . In 1867 , Denver City became the Territorial Capital . With its new @-@ found importance , Denver City shortened its name to Denver . On August 1 , 1876 , Colorado was admitted to the Union . 
