The list below shows what kinds of naturalization records, by county, the Colorado State Archives has in its custody. Before 1906, the primary record series include the Declarations of Intention and Final Papers which were usually filed in a Naturalization Record volume. These earlier naturalization records include less information than later documents. Typically, there is only the applicant's name, the name of the clerk of the court, the name and title of the head of state the applicant renounced allegiance to, and the date of the document. Attached is a Declaration of Intention from Arapahoe County as well as an example of a Final Document  from Arapahoe County from 1891.

After 1906 Colorado counties generally used forms that were created by the Bureau of Immigration and Naturalization. The Pueblo County District Court used a Declaration of Intention form in 1908 that contained detailed personal information about the immigrant. In the Final Petition records, some counties included a copy of the Declaration of Intention (no matter where it was filed), the Certificate of Arrival, and a Petition that may have included a photograph of the person applying for citizenship. The example above illustrates such a record.

Although a state-wide naturalization index does not yet exist, many county indexes are filed at the State Archives for use by researchers. We can also conduct a search for you. However, a naturalization search can be complicated and time consuming, and sometimes a record may not be found. Also, between 1855-1922 alien women were granted automatic citizenship if they were the wife of a U.S. or naturalized citizen. Therefore, we may not have any specific documentation showing the naturalization of a woman during this time period. If you would like us to do a search for you then address all inquiries to the Colorado State Archives. We do have search, handling, and copy fees. Please contact us in order to find out the charges for your request.

The following is a list of counties for which we have naturalization records. We have included the record series title and the approximate date span.

ADAMS COUNTY
Index 1906-1954
Declarations of Intention 1905-1951
Final Documents 1906-1954
Petitions Granted or Denied 1929-1954

ALAMOSA COUNTY
Declarations of Intention 1915-1968
Final Documents 1915-1991

BOULDER COUNTY
Indexes 1872-1958
Declarations of Intention 1872-1958
Final Documents 1879-1958
Certificate of Naturalization Stub Books 1907-1929
Petitions Granted or Denied 1903-1906, 1930-1958

CHAFFEE COUNTY
Declarations of Intention 1881 – 1912
Final Documents 1881 - 1929

CONEJOS COUNTY
Declarations of Intention 1882-1937
Final Documents 1882-1948

COSTILLA COUNTY
Index 1877-1931
Declarations of Intention 1874-1941
Final Documents 1871-1942

CUSTER COUNTY
Index 1881-1927
Declarations of Intention 1876-1940
Final Documents 1881-1941
Certificate of Naturalization Stub Books 1908-1927

DENVER (ARAPAHOE BEFORE 1904)
Indexes 1862-1915
Declarations of Intention 1862-1914
Final Documents 1880-1915

DOLORES COUNTY
Declarations of Intention 1881-1905
Final Documents 1881-1906

DOUGLAS COUNTY
Declarations of Intention 1883-1911
Final Documents 1903-1920
Justice Court Declarations and Finals 1870-1890

EAGLE COUNTY
Declarations of Intention 1883-1904
Final Documents 1883-1904

ELBERT COUNTY
Declarations of Intention 1875-1928
Final Documents 1886-1931
Certificate of Citizenship Stub Book 1913-1917

EL PASO COUNTY
Index 1869-1970
Declarations of Intention 1879-1969
Final Documents 1880-1970
Certificate of Naturalization Stub Books 1907-1927
Witness Depositions 1953-1960
Petitions Granted or Denied 1929-1970
Repatriations 1938-1964
Transfer Petitions 1953-1969

FREMONT COUNTY
Index 1882-1966
Declarations of Intention 1869-1906
Final Documents 1883-1965
Final Oaths 1890-1903
Petition Books 1906-1929

GILPIN COUNTY
Indexes 1869-1917
Declarations of Intention 1861-1941
Final Documents 1863-1941
Certificate of Naturalization Stub Books 1908-1928

HUERFANO COUNTY
Index 1882-1958
Declarations of Intention 1887-1958
Final Documents 1882-1957
Petitions Granted or Denied 1929-1957
Repatriations 1940-1954

JACKSON COUNTY
Index 1910-1940
Declarations of Intention 1910-1940
Final Documents 1932-1940

JEFFERSON COUNTY
Index 1862-1955
Declarations of Intention 1862-1952
Final Documents 1876-1953
Certificate of Naturalization Stub Books 1916-1927
Petitions Granted or Denied 1930-1955

LA PLATA COUNTY
Index 1873-1908
Declarations of Intention 1873-1907
Final Documents 1881-1908

LAS ANIMAS COUNTY
Index 1870-1993
Declarations of Intention 1872-1961
Final Documents 1881-1958
Repatriations 1937-1967

LARIMER COUNTY
Index 1872-1958
Declarations of Intention 1872-1957
Final Documents 1874-1958
Certificate of Naturalization Stub Books 1907-1929

LINCOLN COUNTY
Indexes to Most Volumes Available 1889-1929
Declarations of Intention 1889-1947
Final Documents 1889-1947

MESA COUNTY
Index (District Court Only) 1905-1987
Declarations of Intention 1883-1977
Final Documents 1884-1994
Naturalization Orders 1929-1987
Transfer Petitions 1956-1973
Repatriation Book 1945-1966

MINERAL COUNTY
Declarations of Intention 1893-1905
Final Documents 1893-1904

MOFFAT COUNTY
Index 1902-1959
Index to Declarations of Intention 1912-1928
Declarations of Intention 1905-1929
Index to Certificate of Naturalization Stub Books 1912-1926
Certificate of Naturalization Stub Books 1902-1925
Final Documents 1912-1959

MONTEZUMA COUNTY
Declarations of Intention 1889-1905
Final Documents 1889-1906

MORGAN COUNTY
Declarations of Intention 1889-1952
Final Documents 1907-1958
Orders and Petitions Granted 1929-1958

OURAY COUNTY
Index 1878-1918
Declarations of Intention 1878-1918
Final Documents 1878-1918

PARK COUNTY
Declarations of Intention 1873-1928
Certificate of Naturalization Stub Books 1909-1930
Petitions 1873-1906
Petitions Granted or Denied 1932-1940

PHILLIPS COUNTY
Declarations of Intention 1889-1941
Final Documents 1889-1930

PUEBLO COUNTY
Indexes 1878-1913, 1949-1983
Declarations of Intention 1878-1913, 1949-1978
Transfer Petitions 1953-1976
Petitions Granted or Denied 1949-1985
Repatriations 1949-1969
Final Documents 1877-1913, 1949-1983

RIO GRANDE COUNTY
Declarations of Intention 1874-1906
Final Documents 1874-1906

ROUTT COUNTY
Index 1885-1966
Declarations of Intention 1885-1892, 1907-1963
Certification of Naturalization Stub Books 1907-1926
Petitions Granted or Denied 1930-1967
Repatriations 1940-1957
Final Documents 1885-1892, 1930-1966

SAGUACHE COUNTY
Declarations of Intention 1869-1940
Certificate of Naturalization Stub Books 1907-1923
Final Documents 1878-1940

SAN JUAN COUNTY
Index 1877-1926
Declarations of Intention 1877-1927
Final Documents 1880-1904, 1912-1929

TELLER COUNTY
Index 1899-1941
Declarations of Intention 1899-1941
Final Documents 1899-1941
Certificate of Naturalization Stub Books 1907-1929
Petitions Granted or Denied 1929-1941

WELD COUNTY
Index 1871-1961
Declarations of Intention 1884-1964
Final Documents 1880-1966
Certificate of Naturalization Stub Books 1909-1923

YUMA COUNTY
Declarations of Intention 1906-1940
Final Documents 1904-1941

U.S. DISTRICT COURT FILINGS
DENVER
Dockets 1906-1916
Declarations of Intention 1877-1952
Final Documents 1906-1946

PUEBLO
Declarations of Intention 1906-1949
Final Documents 1912-1949
Miscellaneous Documents 1883-1922

(Note: The Colorado State Archives does not have indexes for the U.S. District Court Filings except for those that exist at the beginning of most volumes. Because of the time involved in searching these records we are unable to conduct the research for patrons. Customers are more than welcome to come in and do the research themselves.)