The Twenty-one-cent Prexie
Chester Arthur became President upon the death of James Garfield, and served the remaining three-and-a-half years of his term. The Arthur portrait on the twenty-one-cent value of the Prexies was taken from a bust by Augustus Saint-Gaudens that stands in the Senate Gallery. Twenty-one-cent stamps were issued in sheet format only. They were first released on November 22, 1938, with a total of 118,616,900 being issued through 1957.
For the most part, twenty-one-cent Prexies were used to pay combinations of postage and fees. These include registered airmail until the registry rate increased in March of 1944, registered airmail to Canada during the same period, registered letter with return receipt, and registered letter with second step indemnity, and a registered local letter at a non-carrier post office at various times.
Another area where solo twenty-one-cent Prexies were used is a special delivery airmail letter from late 1944 to late 1946, and again from 1949 through 1951. Both of these combinations applied to mail to Canada as well.
A certified airmail letter was twenty-one cents from mid-1955 to mid-1957. The other possibilities for solo uses were in connection with third class and fourth class mail and multiple rates.