Prepared by Elisabeth Lindsay.
Naturalization is the process through which those of foreign birth (also referred to as alien) can apply for citizenship in the United States. The primary motivation for citizenship was the right to vote. Naturalization was a lengthy process requiring several years residency and the filing of several "papers" before citizenship was granted. Among these are the Declaration of Intention (first papers); Naturalization Petition - formal application (second papers); Certificate of Naturalization (final papers). In addition, several documents of proof may have been submitted as part of the process, including deposition of witnesses and certificates of arrival (verifying date and port of entry). Information contained in these documents vary, but combined can be a rich source of genealogical information.
Prior to 1906 almost any local court from county to federal could administer naturalization, and papers could be started in one place and completed in another, so knowing where to look can be a challenge for researchers. After 1906 the federal government began regulating naturalizations, with records housed at the National Archives (NARA). Many naturalization indexes are now online. In addition, the U.S. Federal Census at various times asked questions on naturalization: The 1920 census, specifically, asks the year of naturalization. Tracking an immigrant ancestor's movement through the census and examining his response to naturalization questions could narrow the field.