Cover franked with 1929 2 x 10c red & sepia and 15c green & bright violet AIR issue plus 1929 1c bright violet TAX issue (SG 464/465 & 458) tied by MEXICO CITY cds's dated 29 JUL 1929. Flown on the 'Mexico - Tijuana' first flight with boxed first flight cachet in purple on front. Addressed to MORELIA with arrival cds on reverse. (Muller #37)