If your ancestors immigrated to the United States, don't assume that they just came over and stayed here. Often they traveled to their homeland to visit relatives, and they applied for passports to do so. Sometimes we may find old passports in family records that help us know to look for them; other times we may just have to make an educated guess.
Who applied for passports? In the mid-nineteenth century almost all of the applicants were men. This was because if the man was going to be traveling with his wife, children, servants or others under his protection then they would be listed on his passport and application.
Passports were good for two years, so if you find a passport in your family records you can narrow down the application date accordingly. This also means that an individual may have applied for a passport several times during their life, so you should search their entire lifespan, if possible.
Information on passport applications may include name, date. and place of birth; physical description, occupation, foreign destination, naturalization information, and photograph (since 1914). This information should be included for every person listed on the application, including the main applicant and the women or children traveling with him.
One downfall—before 1856, passports could also be issued by other governmental entities, such as local and state authorities or courts. After a Congressional Act in 1856, the U.S. Department of State was granted sole authority to issue passports.
Most of our ancestors would have applied for regular passports. However, there were also three other types of special passports: emergency passports (issued abroad from 1874 to 1926); special diplomatic passports; and insular passports for residents of U.S. territories such as Hawaii (1916-1924), the Philippines (1901-1924) and Puerto Rico (1915-1922).
So how do you find these passport applications? Microfilmed indexes to regular passport applications from 1795 to 1925 are available at the National Archives and Records Administration (NARA) and some of the NARA field branches. The actual applications are also on microfilm. The Family History Library also has copies of some of these microfilms. The U.S. Department of State, not the NARA, has applications since 1925.
Passports and applications should be considered a secondary source for all information except the travel dates and places. If you do find a passport application for an ancestor, try to verify the information as you would with any secondary source. Happy searching!
For more information, visit the National Archives website at http://www.archives.gov/research_room/genealogy/research_topics/passport_applications.html.