The 1947 President's Commission on Higher Education, popularly known as the Truman Commission, offered a remarkable vision, one of an expansive, inclusive and diverse system of postsecondary education in the United States. It appeared just as hundreds of thousands of former GIs poured onto the nation's campuses, taking advantage of a little heralded program to provide tuition and other benefits to veterans of the recently concluded World War II. As it turned out, both of these events signaled the beginning of a remarkable period of expansion in higher education. In this essay, the authors examine the expansion of postsecondary education since 1940, with particular attention to the postwar period in the United States. More specifically, the authors are concerned with the question of access: identifying who entered institutions of higher learning during this time, and how changing patterns in college entry may have altered the makeup of the student body. Using data from the U.S. Census and other sources, the authors analyze national and regional patterns of college enrollment across the four decades before the 1980s. In particular, the authors use 1% samples of youth in 1940, 1960, and 1980 from the Integrated Public Use Microdata Samples (IPUMS), which permit exploration of a number of questions. Besides changes in gender and racial characteristics of students, a variety of other developments affected postsecondary education in these years. Regional differences which had long characterized American education and the postsecondary sector in particular, showed signs of narrowing. Not surprisingly, high school graduation rates were linked to patterns of enrollment in colleges and universities. These too were questions that Commission members had emphasized, calling for greater access to secondary education in all areas of the country. (Contains 49 footnotes and 4 tables.)