Answer: airmail

AnswerCrossword Clue
AIRMAILPostal service.
airmailmail sent by airplane
airmailto send by airplane
airmailthe system of sending mail by airplane
airmailto send mail by airplane
AIRMAILCommunication means since 1911
AIRMAILLindbergh concern, circa 1926
AIRMAILLetters sent by plane
AIRMAILSkywriting?
AIRMAILService begun May 15, 1918
AIRMAILYoung Lindy's cargo
AIRMAILLindbergh's cargo in 1926
AIRMAILKind of postage
AIRMAILKind of stamp
AIRMAILCommunications medium.
AIRMAILFast delivery service?
AIRMAILExpanding Post Office service.
AIRMAILImportant part of Donaldson's work.
AIRMAILPost-office stamp
AIRMAILPost by plane
AIRMAILPostal option
AIRMAILFast delivery
AIRMAILPostal service
AIRMAILPost for quick delivery
AIRMAILMeans to a speedy delivery
AIRMAILSpeedy delivery
AIRMAILSender's option
AIRMAILHigh-flown correspondence?
AIRMAILType of postage stamp