Colorado Military Records
The Colorado State Archives holds the National Guard muster rolls (1861'1919) and the Colorado National Guard service records (1861'1945). The Adjutant General (see Colorado Cemetery Records for address) has a microfilmed copy of the 'Index to Compiled Service Records of the Union Army for Colorado.' This can also be found at National Archives'Rocky Mountain Region, Denver Public Library, and The Family History Library (FHL). Ancestry.com also has a collection compiled by the Adjutant General that lists the names of more than 43,000 Colorado men and women who served in the military during World War I. Subscribers can access this collection at Colorado Soldiers in WWI, 1917-18.
The researcher may also wish to search Sherman Lee Pompey's Confederate Soldiers Buried in Colorado (Independence, Calif.: Historical and Genealogical Publishing Co., 1965) and John H. Nankivel's History of the Military Organizations of the State of Colorado, 1860'1935 (Denver: W. H. Kistler Stationary Co., ca. 1935).
Soldiers' discharge papers for post World War II and later conflicts are located at the county level in the clerk and recorder's office; however, many counties are closing the veterans' discharge papers.