Although the United States was actively involved in World War I for only nineteen months, from April 1917 to November 1918, the mobilization of the economy was extraordinary. ... Over four millionAmericans served in the armed forces, and the U.S. economyturned out a vast supply of raw materials and munitions.
The "boom" years of the 1920's were characterized by a growth in the use of Automobiles.
While looking at the history of the United States, the 'boom years' of the early 1920s were marked by a huge change in the way people traveled.
Personal transportation was shifting from horse-driven carriages to Automobiles, recently mass-produced by Ford.
At the time, the automobiles were a clear sign of growing economic might of the United States and the optimism of the early 1920s.