United States Ship Letter Rates
Effective Date | Postage at Port | Ship Letter Charge In Addition to Inland Postage |
| June 1, 1792 | 4¢ | 4¢ |
| March 2, 1799 | 6¢ | 2¢ |
| July 1, 1851 | 6¢ unpaid 5¢ prepaid | 2¢ |
| February 27, 1861 | 5¢ | 2¢ |
| July 1, 1863 | 4¢ | 3¢ |
United States Rates & Markings
Rates Effective June 1, 1792
Boston
New York
Rates Effective March 2, 1799
Boston (see also Cunard Line mail)
Eastport
Portland
Rates Effective July 1, 1851
Boston
Eastport
Rates Effective February 27, 1861
Portland