In the 1920s and 1930s, when many countries issued airmail stamps to publicise their new airmail routes, a new branch of stamp collecting started. This led to an expansion that includes the collection of covers, and other postal items carried by aircraft.  Airmail items from the early days are expensive due to the popularity of this collecting area.  Specialised catalogues and alblums are produced for collectors of airmail stamps and other areophilatelic items. Many airmail stamps feature aviation themes that are an area of topical stamp collecting.

The first official postage stamp to be issued for an airmail flight was in May 1917 when Poste Italiane overprinted their existing special delivery stamps. The following year, the United State Post Office issued the first airmail stamp specifically issued for the purpose, while it does not have "airmail" or "air post" printed on it, it illustrates a Curtiss JN-4 airplane.