Final answer:
The passage of the Selective Service Act increased the size and strength of the American forces during World War I.
Step-by-step explanation:
The passage of the Selective Service Act had a significant impact on World War I. This act, passed on May 18, 1917, authorized the United States federal government to raise a national army for the war effort. It required all men between the ages of 21 and 30 to register for potential military service. By the end of the war, around 2.8 million men had been drafted into the military through this act, greatly increasing the size and strength of the American forces. The Selective Service Act played a crucial role in providing the necessary manpower to the United States during World War I.
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