Naturalization is the legal procedure by which an alien becomes a citizen of a country. Every nation has different rules that govern these requirements for citizenship. The records generated by the naturalization process can help you learn key information about your immigrant ancestor, including the place of birth and date, ship, and port of arrival. How much you can learn, however, will depend upon when and where the naturalization took place.
Congress passed the first law regulating naturalization in 1790. As a general rule, naturalization was a three-step process that took several years and generated a number of different documents:
First, the prospective citizen filed a declaration of intent, also referred to as first papers, to become a U.S. citizen, in which she renounced allegiance to foreign sovereignties. This document is signed by the immigrant.
Following a prescribed waiting period — generally two to five years — the immigrant could petition a federal court for formal citizenship. This did not have to occur in the same court in which she filed her declaration of intent. The application completed by the individual in this step is called the petition for naturalization.
After the petition was granted, a formal certificate of citizenship was issued to the petitioner.
Typically, the declaration provides more genealogically useful information than the petition. Prior to September 26, 1906, the declaration generally includes the name, country (but not town) of birth or allegiance, the date of the application, and the signature (if the individual being naturalized could write). Many included additional information, but the content varied dramatically from county to county, state to state, and year to year. Naturalizations after September 26, 1906, were handled on standardized forms, and include more detailed information such as the town of birth and the port and date of arrival.
As you can see, September 26, 1906, is a key date for naturalization research. Copies of all naturalizations after that date were forwarded to the newly formed U.S. Bureau of Naturalization for examination and are presently in the custody of U.S. Citizenship and Immigration Services (
For detailed assistance in navigating the maze of available passenger records and locations, turn to the book They Came in Ships: Finding Your Immigrant Ancestor's Arrival Record, third edition, by John P. Colletta, PhD. They Became Americans: Finding Naturalization Records and Ethnic Origins by Loretto D. Szucs suggests a variety of ways to find naturalization records, as well as alternative sources for finding immigrant origins, and includes scores of document examples.
Prior to September 26, 1906, an alien could be naturalized in any court of record — including courts at the local, county, state, or federal level — and the naturalization documents are usually found maintained among the court's records. Often it was a matter of the alien choosing to travel to the most conveniently located court with the authority to naturalize, so you may want to begin your search by identifying the courts closest to the place your ancestor lived at the approximate time she was naturalized. Remember, the approximate year of naturalization can be found on the 1920 census if your ancestor was living at that time.
Some naturalization indexes and records can be found online. Footnote is an excellent source, with digitized indexes and naturalization records for several U.S. states including Maryland, Massachusetts, Pennsylvania, New York, and (Southern) California.
Were They Eligible, or an Exception?
During certain points in American history, a variety of men, women, and children either were eligible to skip a few steps in the naturalization process or were granted automatic citizenship based on eligibility. Minor children, for example, were automatically granted citizenship upon the naturalization of their father. For a time (1855 to 1922), a woman could also achieve automatic citizenship either by marrying a citizen or upon the naturalization of her husband. Conversely, between 1907 and 1922, a female American citizen could lose her citizenship by marrying a man who was a foreign national, even if she never left the United States. From 1824 to 1906, minors who had lived in the United States at least five years before their twenty-third birthday (including those whose parents were not naturalized) were able to skip the declaration step, as were individuals who served in the U.S. armies (Union forces) during the Civil War.
Racial requirements also affected eligibility for naturalization as a U.S. citizen. The naturalization process was first opened to people of African descent on July 14, 1870. Native Americans born outside the United States were barred from citizenship on racial grounds until 1940. The Chinese were the first Asians to gain the right to naturalization, in 1943; most had to wait until 1952, when the racial requirement was stricken from U.S. immigration law.
Not All Aliens Were Naturalized
Aliens living in the United States were not required to become citizens and, during the nineteenth century, it really gained them little other than the right to vote. Alien residents could legally buy and sell property, hold a job, and get married without citizenship status. For this reason, many nineteenth- and early-twentieth-century immigrants — at least 25 percent according to answers recorded in the 1890 through 1930 censuses — lived most of their lives in the United States as aliens and either never began or never completed the process of naturalization.
If census or other records lead you to believe that your ancestor never pursued naturalization, don't despair. Alien registration and visa records are often similarly rich in genealogical details. Information was collected on non-citizen residents of the United States at various points during American history, including special wartime registrations of alien citizens of “enemy” countries and a nationwide registration effort in the 1940s. Beginning in 1924, aliens arriving in the United States were required to apply for immigrant visas, which offer yet another source for information on foreign-born residents.
The Immigration Act of 1924 prompted a major change in U.S. immigration. Beginning July 1 of that year, everyone arriving at a U.S. port of entry was required to present some type of entry document. This might include a birth record or naturalization certificate for U.S. citizens, a reentry permit for alien residents of the United States, or an immigrant visa or other paperwork for noncitizens. Prospective immigrants wishing to settle in the United States were required to apply for an immigrant visa at a U.S. embassy abroad. Those traveling to the United States for a temporary purpose, such as a visit or to attend school, applied for a nonimmigrant visa.
U.S. Citizenship and Immigration Services (USCIS) (
Fears of unknown enemies living within the United States prompted registration of resident aliens during wartime. These enemy alien registration records covered aliens who were living in the United States and were citizens of a country against which the United States had declared war.
The first such large-scale effort was prompted by World War I, when from November 1917 to April 1918 all resident, non-naturalized “enemy” aliens, including their American-born wives, if applicable, were required to register with the U.S. Marshal in their county of residence as a national security measure. These alien registration forms documented citizens of the German empire living in the United States, including the date and ship of arrival, children's names and birth dates, parents' names and address, whether the alien was sympathetic to the enemy, names of relatives serving in the enemy forces, occupation and employer, a physical description, and a photograph and full set of fingerprints.
The majority of the World War I enemy alien records were destroyed in the 1920s by authority of Congress, but state and/or local copies of records for Kansas, Minnesota, Missouri, and the Phoenix, Arizona, area, as well as a few scattered other registrations, still survive. Selected records can be found online, such as this index to Enemy Alien Registration Affidavits, 1917–1921, of Kansas (
The Alien Registration Act of 1940 required all alien residents age fourteen and older to register with the U.S. government and be fingerprinted. Aliens entering the country registered as they applied for admission. This alien registration requirement applied to all aliens over the age of fourteen, regardless of their nationality and immigration status. Millions of the aliens who registered had already lived in the United States for many years.
Alien registrations completed between July 1940 and April 1944 were microfilmed and placed in the custody of U.S. Citizenship and Immigration Services. These records are searchable by name, date of birth, and place of birth, and copies may be obtained through the USCIS Genealogy Program.