History
Arapahoe County calls itself "Colorado's First County" since its origins predate the Pike's Peak Gold Rush.
On August 25, 1855, the Kansas Territorial Legislature created a huge Arapahoe County to govern the entire western portion of the Territory of Kansas. The county was named for the Arapaho Nation of Native Americans that lived in the region.
Arapahoe County is a county in the State of Colorado of the United States. The United States Census Bureau estimates that the county population was 637,068 in 2016. The county seat is Littleton.