College enrollment in the U.S. increased following the passage of The Servicemen's Readjustment Act of 1944, commonly known as the GI Bill.
The GI Bill, which provided funding for tuition and living expenses for veterans to continue their education, was passed near the end of World War II to avoid mass unemployment as the 15 million men and women who fought in the war began to return to the U.S.
According to the Our Documents Initiative, “the number of degrees awarded by U.S. colleges and universities more than doubled between 1940 and 1950, and the percentage of Americans with bachelor degrees, or advanced degrees, rose from 4.6% in 1945 to 25% a half-century later.”
The National Center for Education Statistics concurs that “college enrollment increased as many war veterans took advantage of the GI Bill of Rights to attend the nation’s institutions of higher education.”