Naturalizations before 1906 could be done in any just about any court in the country, and were not standardized. After 1906 the federal government took over the naturalization process and all forms became standardized nationwide. The repositories for naturalization granted from1906-1995 are generally located at the place in which the person naturalized (e.g. County Court, District Court, etc.). Most District Court naturalizations have been transferred to the National Archives and Records Administration. In addition, copies of the Petition for Naturalization and Certificate of Naturalization were sent to Immigration and Naturalization Services which is now US Citizenship and Immigration Services. To have us conduct the naturalization record search pertaining to your ancestor click here.
How do I find out if my Italian ancestor became a US Citizen (i.e. naturalized)?