Arapahoe County, Kansas Territory

The county was named for the Arapaho Nation of Native Americans that lived in the region.

Following the Republican Party election victories in 1860, the United States Congress admitted Kansas to the Union on January 29, 1861.

[1] The Kansas Act of Admission excluded the portion of the Kansas Territory west of the 25th meridian west from Washington from the new state, and Arapahoe County and the rest of this region reverted to unorganized territory.

Another Arapahoe County existed in southwestern Kansas around 1880, when its population was included in the Federal census of that year, but it was never organized.

It became defunct in 1883 and its former area was established in 1887 as Haskell County, Kansas.