Colorado Naturalization and Citizenship
Naturalization records were filed in local or federal courts until 1906 when the U.S. district courts were given jurisdiction. Some territorial and early statehood records for Colorado are at the Colorado Division of Archives and Public Records. The National Archives Rocky Mountain Region (Denver) has declarations and petitions for the years 1877 to 1952 for the U.S. District Courts of Denver, Pueblo, Del Norte, and Montrose. The U.S. District Court in Denver has an index to naturalizations granted in these courts since 1876.
The Family History Library has microfilms of U.S. District Courts Naturalization Records for Denver (1877-1952) and Pueblo for the years (1906-1949).
The Colorado Genealogical Societyhas indexed abstracts of some naturalization records and published these in The Colorado Genealogist (see the "Periodicals" section).
In 1906 the Immigration and Naturalization Service (now United States Citizenship and Immigration Services) was created, forms were standardized and duplicate records created by the court were sent to the INS. To access these records, download a FOIA (Freedom of Information Act) form from www.uscis.gov, fill it in and send it to the address listed on the form. You may also contact the National Archives Rocky Mountain Region (Denver), or order films from the Family History Library. The library has naturalization records from 1877 to 1952.