This striking First Day Cover from the 1983 Hot Air Ballooning series (Scott #2033, part of the block) honors Explorer II, the massive helium balloon that, on November 11, 1935, carried U.S. Army Air Corps captains Albert W. Stevens and Orvil A. Anderson to a record altitude of 72,395 feet—higher than any human had flown before—providing valuable data on the stratosphere. The 20¢ stamp depicts the sleek, silver Explorer II balloon ascending vertically against a blue sky. The cachet artwork, signed by Koslow, shows a breathtaking aerial view of the balloon's enormous silver envelope towering above a forested landscape and launch site, with the gondola visible at the bottom and a circular landing area below, capturing the scale and daring of the 1930s high-altitude expedition. Postmarked March 31, 1983 (issue date), in Albuquerque, New Mexico (joint first-day city with Washington, DC), with a sharp "First Day of Issue" cancellation (ZIP 87101). This cover captivates aviation history collectors, ballooning and stratosphere exploration enthusiasts, 1930s science philatelists, or completists of the Hot Air Ballooning set. It remains in excellent unaddressed vintage condition with vivid metallic tones, clean lines, and no wear, perfect for thematic or aerospace displays.
