Source Information U.S., Applications for Seaman's Protection Certificates, 1916-1940 [database on-line]. Lehi, UT, USA: Operations, Inc., 2010.
Original data:

Application for Seaman's Protection Certificates, 1916-1940. 1151 Boxes. NAID: 2788575. Records of the Bureau of Marine Inspection and Navigation, 1774-1982, Record Group 41. The National Archives in Washington, D.C.

About U.S., Applications for Seaman's Protection Certificates, 1916-1940

This series contains documents which served as seamen's passports. They were issued at all ocean and Great Lakes ports by the collector of customs or his deputy, usually in his capacity as shipping commissioner. A typical application contains the seaman's name, the date and place of his birth, his address, signature, thumb print, a photograph, his present or prospective rating, and the name of the vessel on which he served or was expected to join. As evidence of citizenship, birth certificates, affidavits by relatives or friends, or citations to naturalization proceedings were frequently appended.

Records from individual ports sometimes include one or more of the following: 1) copies of the citizen seaman's identification card that usually contains a seaman's name, nationality, age, birthplace, brief physical description, and photograph; the birth places of his parents; and the place and date of his naturalization when applicable; 2) seaman's identification cards for aliens, not issued after 1919, which usually contain a seaman's name, nationality, age, signature, photograph, brief physical description, and name and nationality of his vessel; 3) lists of men who received these documents; and 4) indexes to the documents.

Note: The above information on this series comes from The National Archives Catalog.