Wave of Immigration
1917 - America joins World War I.
World War I began in 1914, but America did not enter the war until 1917. The drafting and training of a large expeditionary force was the largest undertaking of the federal government since the Civil War.
As part of the effort to raise and train a large force, the U.S. Army employed psychologists to give intelligence tests to the recruits. This was the first mass application of standardized tests to millions of people for classification purposes.