In the United States, the
naturalization process began with a
declaration of the immigrant's intent to
citizen. Three years after this declaration was filed—and five
years after arriving in the country—a petition for naturalization could
be filed, in the same or a different court. A
certificate of citizenship could then be issued. Until 1922, a
foreign-born woman married to a naturalized citizen was automatically
made a citizen. Until 1940, a child under the age of 21 was
granted citizenship based on the status of his father. (For
other exceptions, see the
National Archives website.)
In U.S. census records from 1900
on, the year of arrival of each naturalized or unnaturalized immigrant
was to be recorded. Also recorded was the naturalization status
of the immigrant, whether he was an alien ("Al"), had filed his first
papers ("Pa"), or had been naturalized ("Na").
What the Records Show
Early naturalization records vary greatly in genealogical value. The Declaration of Intent will generally be most useful, and may provide the immigrant's date of birth, his town or county of origin, the dates and places of his departure and arrival, and his residence since emigrating. Or it may provide very little information.
At the very least, one may find in naturalization records the date one's ancestor became a citizen. This, in itself, would be a valuable discovery.
One should approach the dates reported in naturalization records with caution. A study in Sonoma County, California, described in Carmen J. Finley's "Original Naturalization Records: A Reliable Source for Birth Dates?" (National Genealogical Society Quarterly 91:60 (Mar. 2003)), found a 1.3% error rate in birth dates recorded in multiple files—discrepancies ranging from a few days to 23 years (the latter probably due to a clerical error). As this error rate is only for records in which a birth date was repeated, the actual error rate in reported birth dates is probably much higher. (Anecdotal evidence supports this conclusion.) Dates of emigration are often mistaken as well.
From 1790 until 1906, naturalization records could be filed
with any court. Thus, records of citizenship granted
prior to 1906 are scattered throughout municipal, county, state and
Federal court records, and may be difficult for the genealogist to
track down. The National Archives does have indexes for
naturalizations which occurred in state and local courts in New England, New York City, and the
District of Illinois prior to 1906, and maintains all records of
U.S. naturalizations performed since then. Additional indexes for
non-federal jurisdictions are available online—some for free and
others not—and on microfilm at your local Family History Center.