Most of the mail exchanged between the United States and the Maritime provinces originated and terminated in these countries. However, mail to and from third countries was occasionally exchanged between the United States and the Maritime provinces. On rare occasions, mail also transited a third country (generally Canada) between the United States and the Maritimes. In many cases, the mail was sent to from or through the third country due to the lack of a direct mail route. However, these covers also resulted from missent mail and interruptions in mail service, such as shipwrecks.
 | Confederate States of America |
 | Kingdom of Hawaii Hawaii to New Brunswick via United States |
 | Canada East and Canada West |
 | British Columbia and Vancouver Island |
 | Newfoundland |
 | St. Pierre et Miquelon |
 | Great Britain |
 | Brazil |
 | Cuba |
 | Jamaica |
 | |
Missent and Interrupted Mail