The Twenty-one-cent Prexie
Registered airmail use
The minimum registry fee was fifteen cents from April 15, 1925 until March 26, 1944. Combined with an airmail rate of six cents, the franking would provide an opportunity for use of a solo twenty-one-cent Prexie.
The domestic airmail rate was six cents per ounce from July 1, 1934 until March 26, 1944. This registered airmail cover was sent from Los Angeles to Warren, Ohio in March of 1940.
A six cents per half ounce military airmail rate for servicemen outside the continental U.S. and, later, some other personnel, was in effect from December 25, 1941 until October 1, 1946. This registered airmail cover was sent from a serviceman stationed at Schofield Barracks, Oahu on March 15 of 1944, shortly before the minimum registry rate increased to eighteen cents.
The military concession airmail rate also applied to mail sent to servicemen outside the continental U.S. This registered cover was sent to a serviceman in the navy on February 28, 1944, and was forwarded a number of times, appearing to have reached him in the Naval Hospital in Oakland on April 12.
Even though a territory, Alaska used the same airmail rates as the Lower 48. This cover was sent registered airmail from Juneau to Milwaukee in 1942.
The same rates applied to mail going the other direction, Lower 48 to Alaska. This cover was sent registered airmail from Boise to Nome in 1942.