Co-blogger Frank (below) notes that the undergrad population at his institution, Berry College, is now nearly two-thirds female. That’s an uncommonly high percentage, but indicative of the trend: the total U. S. undergraduate population has gone from under to over 50% female in the last twenty-five years, and the female majority is growing.

Robert J. Samuelson reports that “Women now earn a third more bachelor's degrees than men (712,331 against 531,840 in 2001).” The National Center for Educational Statistics reports: “In 2000, females accounted for 55 percent of full-time enrollment and 58 percent of part-time enrollment.”

What is driving the increasing percentage of female undergraduates? I hypothesize the combination of two things: the higher variance of males’ academic talents (the “males at the tails” phenomenon), combined with the expansion of higher education to accommodate more than half of the college-age population. Suppose that the male and female talent distributions have the same mean, and that each sex is half of the population, but that male distribution has a larger variance. The female distribution is then more highly peaked at the mean. As college attendance goes from 50% toward 60% or more of the total population, more women will be added than men (if the admission decision is by talent). With men over-represented in the lower tail of the academic-talent distribution, they are increasingly under-represented in the college population.

I haven't found the actual college-going percentage, but it’s clearly above 60%, based on these figures from a University of Maryland site. From 1980 to 2000, “For families with incomes below $33,000, the college-attendance rate increased from about 40 percent to nearly 60 percent. For families with incomes above $80,000, the college-attendance rate increased from about 70 percent to about 83 percent.”

As the baby boom fades, and colleges with excess capacity dip deeper into the college-age pool to fill their dorms, the percentage attending college can be expected to continue rising. But the percentage of undergrads who are female won’t necessarily keep rising: that depends on whether the percentage of females in the marginal percentile being added continues to exceed their percentage in the existing college population. Beyond some point, the percentage of males begins to rise again (it would have to return to 50%, once everybody attends college).