The twelve-cent Prexie
The twelfth President was Zachary Taylor, who served from March 5, 1849 until his death on July 9, 1850. His likeness on the twelve-cent definitive stamp of 1938 was taken from a bust in the Virginia State Capitol. Twelve-cent Prexies were only issued in sheet format.
The first release of the twelve-cent Prexie was on September 14, 1938. A total of 664,333,800 were issued through 1959.
The twelve-cent Prexie had very few domestic single-rate usages, all fourth class.
Other single-rate solo uses involved half-ounce airmail postage to El Salvador, Guatemala, Honduras and Nicaragua.
Twelve cents was the cost of a local special delivery letter early in the period, as well as a special delivery postcard to Canada. For a short time in the late 1950's it was also the rate for third class mail with minimum insurance.
Other solo uses include multiple first class and double airmail postage, multiple third class charges and parcel post rates for more than one pound, and multiple PUAS surface postage. And from November of 1953 until August 1958 twelve cents was the cost of a double weight surface letter to a UPU country.
A certificate of mailing for multiple items can result in any value of Prexie being used.