On August 25, 1855, the Kansas Territorial Legislature created a huge Arapahoe County [see the map showing the evolution of counties in Colorado] 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.

In July 1858, gold was discovered along the South Platte River in Arapahoe County (in present day Englewood). This discovery precipitated the Pike's Peak Gold Rush. Many residents of the mining region felt disconnected from the remote territorial governments of Kansas and Nebraska, so they voted to form their own Territory of Jefferson on October 24, 1859. The following month, the Jefferson Territorial Legislature organized 12 counties for the new territory, including a new Arapahoe CountyDenver City served as the county seat of Arapahoe County. 

The Jefferson Territory never received federal sanction, but on February 28, 1861, U.S. President James Buchanan signed an act organizing the Territory of Colorado.  On November 1, 1861, the Colorado General Assembly organized the 17 original counties of Colorado including a new Arapahoe County. Arapahoe County originally stretched from the line of present-day Sheridan Boulevard 160 miles (258 kilometers) east to the Kansas state border, and from the line of present-day County Line Road 30 miles (48 kilometers) north to the Parallel 40° North (168th Avenue). Denver City served as the county seat of Arapahoe County until 1902.  

In 1901, the Colorado General Assembly voted to split Arapahoe County into three parts: a new consolidated City and County of Denver, a new 

Adams County, and the remainder of the Arapahoe County to be renamed South Arapahoe County. A ruling by the Colorado Supreme Court, subsequent legislation, and a referendum delayed the reorganization until November 15, 1902. Governor James Bradley Orman designated Littleton as the temporary county seat of South Arapahoe County. On April 11, 1903, the Colorado General Assembly changed the name of South Arapahoe County back to Arapahoe County. On November 8, 1904, Arapahoe County voters chose Littleton over Englewood by a vote of 1310 to 829 to be the permanent county seat.




My name is Denise. I am the Arapahoe County Coordinator. Although I do not live in Arapahoe County, I have always been fascinated with it and with Denver. I would love to have your help in bringing new information and data to this website. If you have any items to donate, please feel free to contact
me. We never know what we have to contribute that could make a difference for another family researcher, so don't be shy! 

I do not have any personal resources for lookups but there are others who have volunteered their personal time and resources to do lookups for others. If you have any Arapahoe County resources and would like to volunteer as well, please email me.

Colorado Books - a new site brought to you by the Denver County coordinator.  Check it out!  Added here September 2011 in progress. 

NEW ADDITION:  Working on the 1870 Federal Census - pages 1-3 online under Census


Neighboring Counties

 Location    County   
 North     Adams
 East Washington
 South Elbert
 South Douglas
 West Jefferson
 West Denver

Thank you for visiting Arapahoe County, COGenWeb!

Last updated JULY 2019

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