Centenary of establishment of regular Airmail Service in USA (United States of America 2018)

Stamp Centenary of establishment of regular Airmail Service in USA it reflects the thematic directions:

An aircraft (pl. aircraft) is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, rotorcraft (including helicopters), airships (including blimps), gliders, paramotors, and hot air balloons.Part 1 (Definitions and Abbreviations) of Subchapter A of Chapter I of Title 14 of the U. S. Code of Federal Regulations states that aircraft "means a device that is used or intended to be used for flight in the air."

Postal history is the study of postal systems and how they operate and, or, the study of the use of postage stamps and covers and associated postal artifacts illustrating historical episodes in the development of postal systems. The term is attributed to Robson Lowe, a professional philatelist, stamp dealer and stamp auctioneer, who made the first organised study of the subject in the 1930s and described philatelists as "students of science", but postal historians as "students of humanity". More precisely, philatelists describe postal history as the study of rates, routes, markings, and means (of transport).