Example image of eyePlorer eyePlorer map for 'Jefferson Territory': 1859 1861 Colorado Territory February 28 October 24 Organic Act United States United States territory Kansas Territory Nebraska Territory New Mexico Territory Utah Territory Washington Territory Federal government of the United States Colorado General Assembly 1855 Arapahoe County, Kansas Territory August 25 Arapaho Cheyenne Bleeding Kansas Slave state United States Congress March 28 Auraria, Denver Denver February 7 June 6 August 1 September 24 October 3 Thomas Jefferson United States Declaration of Independence 1803 Louisiana Purchase President of the United States Colorado 102nd meridian west 110th meridian west 37th parallel north 43rd parallel north December 7 December 8 1860 January 23 Robert Williamson Steele 1860 United States Census August 7 Abraham Lincoln Confederate States of America