2-4 Post Routes (39 CFR 310.1(d))

Post routes are routes on which mail is carried by the Postal Service. They include post roads as defined in 39 U.S.C. 5003, as follows:

1. The waters of the United States, during the time the mail is carried thereon.
2. Railroads or parts of railroads and air routes in operation.
3. Canals, during the time the mail is carried thereon.
4. Public roads, highways, and toll roads, during the time the mail is carried thereon.
5. Letter-carrier routes established for the collection and delivery of mail.