From the initiation of regular U.S. transcontinental airmail service until the onset of the U.S. entry into World War II (7 December 1941), the world witnessed a dramatic evolution of commercial air travel. During this time, airmail rates underwent substantial revisions which continued through the onset of World War II. Ultimately, war forced airlines to modify or close many routes.
Perhaps reminiscent of the complex pre-Universal Postal Union (U.P.U.) period of transoceanic ship mail (1838-1875) to the eventual establishment of the U.P.U. standard rate system, the once complex airmail rate structure (e.g., sanctioned use of mixed franking, highly diverse selection of routes and rates, and the cobbling of agreements between countries to establish new postal routes) gave rise to a simpler standard airmail rate structure which we use today.
The era had a significant and lasting effect on worldwide airmail service that can still be observed today. Few time periods are as influential to al