The listing, MINT 1927 20¢ Airmail Perf 11 - US Scott # C9 has ended.
U.S. #C9
1927 20¢ U.S. Map and Mail Planes
Issue Date: January 25, 1927
City: Washington, DC
Quantity: 17,616,350
Printed By: Bureau of Engraving and Printing
Printing Method: Flat plate printing
Perforations: 11
Color: Yellow green
In 1927, the airmail rate was changed to 10¢ per half ounce, regardless of distance. Because most airmail letters weighed more than one-half ounce, it was necessary to prepare this 20¢ stamp. Like the 10¢ and 15¢ issues released before it, the new stamp was printed in a larger, more distinctive size than the earliest airmail issues. Post Office clerks were easily able to distinguish these from ordinary postal stamps.