Have you found a seafaring person in your tree? Then you should definitely check out what I consider one of the best records out there and one of my personal favorites! They are just so very fascinating.
The Citizenship Affidavits of US-born Seaman at Select Ports, or Seaman’s Protection Papers as they’re sometimes known, were issued starting in the early 1800’s as a way to protect US sailors from being “pressed” into service on British ships. Think of it like a passport type of identification… applicants would go to a local official and have their identity verified. This usually included either bringing an person with you who knew you or providing signed affidavits from witnesses who attested to your identity and proof of citizenship or a notarized affidavit of such.