"New York Aug 11" double circle datestamp addressed to the U.S. Coast Survey in San Francisco. This cover pays the 10c transcontinental rate (for mail traveling over 3,000 miles) plus the 1c carrier fee for collection service in New York City.
Only 17 such covers are recorded combining 10c general issue with a 1c carrier stamp to pay the full 11c rate; this is one of just 9 known examples bearing the 1861 1c Blue. Scarce and desirable usage illustrating the intersection of carrier service and long-distance domestic mail. Partial backflap.
Included as #12 in Clifford Alexander's Census
Included in Donald L. Evans' Exhibit and Book, page 323, "The United States 1c Franklin 1861 -1867 and An Introduction to the Postal History of the Period," (Linn's Stamp News 1997)