Prepared by Elisabeth Lindsay.
A C-File is the abbreviated name for the naturalization Certificate Files created as a result of the Naturalization Act of 1906 to contain and store duplicate copies of all court naturalization records. C-Files were also created from alien registration A-Files when the immigrant became naturalized.
C-Files dated 1906 to 1944, numbered C-1 to C-650000, were microfilmed in the 1950s and the originals destroyed; only a few paper records from that period survive. "Consolidated C-Files" are those dated to March 31, 1956, and numbered C-650000 to C-770000.
In addition to immigrant name, date and place of birth and port of arrival, C-Files contain an immigrant's Declaration of Intention, Petition for Naturalization, and Certificate of Naturalization, but may contain other documents, depending on the law applicable at the time they applied. Some C-Files contain information pertinent to derivative citizenship, resumed citizenship and repatriation, and may include other information such as applications for replacement certificates; proof of citizenship in relation to job applications, background investigations, insurance claims, or pension benefits. Both C-Files and A-Files can be accessed through the United States Citizenship and Immigration Service (USCIS) Genealogy Program.