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Jefferson County, Colorado

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Please add profiles of those who were born, lived or died in Jefferson County, Colorado.

Official Website

On August 25, 1855, the Kansas Territorial Legislature created Arapahoe County to govern the entire western portion of the territory. The county was named for the Arapaho Nation of Native Americans that lived in the region.

On June 22, 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. Jefferson County was named for the namesake of the Jefferson Territory, Thomas Jefferson, the principal author of the Declaration of Independence and the nation's third president.

A major employer in Jefferson County is the large Coors Brewing Company in Golden. Also, the state-supported Colorado School of Mines is located in Jefferson County, focusing on topics such as mining, geology, chemistry, and engineering.

The Columbine High School Massacre occurred in the county on April 20, 1999.

Adjacent Counties

Cities & Towns

  • Arvada (part)
  • Bow Mar
  • Edgewater
  • Golden (County Seat)
  • Lakeside
  • Lakewood
  • Littleton (part)
  • Morrison
  • Mountain View
  • Superior (part)
  • Westminster (part)
  • Wheat Ridge

Other Communities: Applewood, Aspen Park, Buffalo Creek, Coal Creek (part), Columbine, Conifer, Dakota Ridge, East Pleasant View, Evergreen, Fairmount, Foxton, Genesee, Idledale, Indian Hills, Ken Caryl, Kittredge, Pine, Pine Junction and West Pleasantview



National Register of Historic Places

Pike's Peak Gold Rush

Pike National Forest

Roosevelt National Forest

Lost Creek Wilderness

Rocky Flats National Wildlife Refuge

Two Ponds National Wildlife Refuge

CO Gen Web

Genealogy Trails

Jefferson County Archives

Golden History Museum & Park