America – 45¢: The 1990 airmail stamp, issued by the Postal Union of the Americas and Spain, features a Caribbean island beach like that discovered by Columbus. It was printed together with the 25¢ America issue on one quadrant of the same sheet.
Harriet Quimby – 50¢: One of the few women honored on Airmail stamps is Harriet Quimby, journalist and drama critic. She was the first American woman to receive a pilot’s license, and the first woman to fly the English Channel solo.
William T. Piper – 40¢: Designer of the popular Piper Cub plane, he was called the “Henry Ford” of aviation for developing and promoting low-cost aircraft.
Antarctic Treaty – 50¢: This treaty, which went into effect on June 23, 1961, demilitarized the continent of Antarctica and preserved it for scientific research. This stamp honors the treaty’s 30th anniversary.
America – 50¢: The 1991 America stamp shows what the Bering Strait, which linked Siberia and Alaska, may have looked like to Asians crossing it thousands of years ago. The America Series was begun in 1989 by the Postal Union of the Americas and Spain. Portugal became a member in 1991.