Red "New York Dec 10" with red "MAIL ROUTE" marking. Manuscript "24" and "Ship Illinois Capt. Waterman" on 1828 folded letter to Boston.

The "Mail Route" marking was applied from 1827 to 1830 to private ship letters that were not classified as "Ship Letters" under the "impliedly under contract" ruling by the Post Office Department. This allowed these letters to be treated as though they were part of official postal routes, resulting in higher inland postage charges. This discriminatory practice was discontinued in 1830, as it faced criticism for unfairly inflating rates on non-contract ship letters.

This letter was carried on the ship Illinois. 2c Ship fee not added because vessel was an implied contract ship.

Rated for the distance down the Mississippi River and over Long Ssland Sound (12 12 1/2 c for 80-150 miles) but not including the part of the voyage over the Atlantic Ocean (which was not an official post road).