In 1861, when Kansas became a state, Colorado was established as a territory with Arapahoe County as one of the original 17 counties. This county was named after the Arapaho Indians, who had inhabited the area for centuries. The Arapahoe Greenway (AH1) is a series of paved trails and parks that follow the banks of the South Platte River and its tributaries, connecting with those of neighboring counties. Governor James Bradley Orman designated Littleton as the temporary seat of South Arapahoe County. Arapahoe County is governed by its Board of County Commissioners, which serves as the county's administrative and policy-making body.
It is home to some of the largest companies in the country, representing a variety of industries such as aerospace and defense, life sciences, broadband, construction, engineering, financial services, healthcare, hospitality, information technology, and advanced manufacturing. Originally, Arapahoe County extended from the line of present-day Sheridan Boulevard east to the Kansas border and from the line of the current highway that borders the county north to the 40th parallel north (168 Avenue). In July 1858, gold was discovered along the South Platte River in Englewood. The following month, the Jefferson Territorial Legislature organized 12 counties for the new territory, including a smaller Arapahoe County. On April 11, 1903, the Colorado General Assembly changed the name of South Arapahoe County to Arapahoe County. On November 8, 1904, Arapahoe County voters chose Littleton instead of Englewood by 1310 to 829 to be the permanent county seat. Arapahoe County is known as 'the first county in Colorado' since its origins predate even the Pike's Peak gold rush.
It is a constitutional subdivision of the government of Colorado and can only exercise powers specifically expressed in statutes or in the state constitution. In 1901, the Colorado General Assembly voted to divide Arapahoe County into three parts: a new consolidated city and county of Denver, a new Adams County, and the rest of Arapahoe County which was renamed South Arapahoe County.