Brown & McGill's U.S.P.O. Despatch, 5LB2, 2c Blue with #26 3c Dull Red, Both Tied by Blue Circular Grid on Cover

#1 in the Brown & McGill's U.S.P.O. Despatch, The Blue Stamp, 5LB2 Census by Larry Lyons
The 5LB2 with large to huge margin, tied by blue 6 bar grid with matching "Louisville Ky. Aug. 4, 1860" circular datestamp. Addressed from Louisville, KY to Mt. Sterling, Ohio. The carrier stamp with tiny toned specks and a tiny scuff at top left margin, the 3c with a few short perfs.
A VERY FINE AND BEAUTIFUL EXAMPLE OF THE BROWN & McGILL'S CARRIER STAMP TIED BY LOUISVILLE GRID CANCEL. ONLY SIX OR SEVEN COVERS ARE KNOWN WITH THIS TIED USAGE, AND THIS IS ONE OF THE TWO FINEST RECORDED.