First Flight cover with typed 'First Flight Puerto Barrios Guatemala, Merida Mexico, and New York, U.S.A.' at top franked with 1931 'Primer Vuelo Postal BARRIOS MIAMI 1931' overprint issue set of three (SG 264/266) tied by large boxed 'VUELO INAUGURAL DE LA RUTA BARRIOS - MIAMI 5 DICIEMBRE 1931' cachet with PUERTO BARRIOS cds dated 5 DIC 1931 alongside. Flown on the PUERTO BARRIOS - MERIDA, MEXICO first flight without any Mexican transit marks. Addressed to NEW YORK, USA with interesting 'Emilio Castanando' signature in purple on reverse who was very likely the pilot. Very scarce. (Muller #52, Goodman #AM32e)