by the U.S. in wartime were from Britain or France. In August 1917, Congress passed the Aero Bill which dedicated $640 million towards aircraft production; however, the U.S. economy overall was unable to successfully transition into a mass-producing aircraft industry in such a short amount of time. Post WWI Era (1918–1930s) After the first World War, the U.S. aircraft industry declined and stagnated, due to low budgets, low demand, and the high competition from foreign manufacturers who already possessed technology far more advanced than the U.S. did. Because the bulk of the aircraft demand had come from military uses, the post-war period resulted in a surplus of aircraft left over from wartime accompanied by a lack of demand, creating an excess supply of unused aircraft. Military aviation dominated the aircraft industry up until the mid-1920s, and it was during the late 1920s when civil aviation appeared and began to rise. Beginning in the mid-1920s, in order to sustain the existence of the aircraft industry, the U.S. government endorsed and subsidized airlines to carry airmail throughout the country, leading to the U.S. having the largest airmail system in the world. The U.S. implemented the Kelly Airmail Act of 1925 which induced competition amongst airlines and eventually led to the expansion from carrying mail to carrying people and commercial goods. The emergence of an expansive airmail system allowed for easier and faster correspondence and transport. Aircraft as a means of passenger travel also began to emerge during this time period, though passenger air travel did not surge until after World War II. Unemployment was not significantly affected by the emergence of the civil aviation industry, as the jobs that were created were occupied by people who previously worked in the army and were then unemployed after the war's end. World War II U.S. aircraft production surged throughout World War II. The U.S. experienced an immense amount of government spending on defense production and a shift from automobile production to aircraft production. At the beginning of the war, the U.S.' aircraft production was one of the lowest in the world, but by 1945, the U.S. aircraft production alone had already produced more than a third of the world's total aircraft production. Aircraft production made up the most of the U.S.' manufacturing output during the World War II era from 1940 to 1945, contributing to the surge in GDP growth. The expansion of the