ANOTHER ladies’ night, not by choice.

After midnight on a rainy night last week in Chapel Hill, N.C., a large group of sorority women at the University of North Carolina squeezed into the corner booth of a gritty basement bar. Bathed in a neon glow, they splashed beer from pitchers, traded jokes and belted out lyrics to a Taylor Swift heartache anthem thundering overhead. As a night out, it had everything — except guys.

“This is so typical, like all nights, 10 out of 10,” said Kate Andrew, a senior from Albemarle, N.C. The experience has grown tiresome: they slip on tight-fitting tops, hair sculpted, makeup just so, all for the benefit of one another, Ms. Andrew said, “because there are no guys.”

North Carolina, with a student body that is nearly 60 percent female, is just one of many large universities that at times feel eerily like women’s colleges. Women have represented about 57 percent of enrollments at American colleges since at least 2000, according to a recent report by the American Council on Education. Researchers there cite several reasons: women tend to have higher grades; men tend to drop out in disproportionate numbers; and female enrollment skews higher among older students, low-income students, and black and Hispanic students.

In terms of academic advancement, this is hardly the worst news for women — hoist a mug for female achievement. And certainly, women are primarily in college not because they are looking for men, but because they want to earn a degree.

But surrounded by so many other successful women, they often find it harder than expected to find a date on a Friday night.

“My parents think there is something wrong with me because I don’t have a boyfriend, and I don’t hang out with a lot of guys,” said Ms. Andrew, who had a large circle of male friends in high school.

Jayne Dallas, a senior studying advertising who was seated across the table, grumbled that the population of male undergraduates was even smaller when you looked at it as a dating pool. “Out of that 40 percent, there are maybe 20 percent that we would consider, and out of those 20, 10 have girlfriends, so all the girls are fighting over that other 10 percent,” she said.

Needless to say, this puts guys in a position to play the field, and tends to mean that even the ones willing to make a commitment come with storied romantic histories. Rachel Sasser, a senior history major at the table, said that before she and her boyfriend started dating, he had “hooked up with a least five of my friends in my sorority — that I know of.”

These sorts of romantic complications are hardly confined to North Carolina, an academically rigorous school where most students spend more time studying than socializing. The gender imbalance is also pronounced at some private colleges, such as New York University and Lewis & Clark in Portland, Ore., and large public universities in states like California, Florida and Georgia. The College of Charleston, a public liberal arts college in South Carolina, is 66 percent female. Some women at the University of Vermont, with an undergraduate body that is 55 percent female, sardonically refer to their college town, Burlington, as “Girlington.”

The gender gap is not universal. The Ivy League schools are largely equal in gender, and some still tilt male. But at some schools, efforts to balance the numbers have been met with complaints that less-qualified men are being admitted over more-qualified women. In December, the United States Commission on Civil Rights moved to subpoena admissions data from 19 public and private colleges to look at whether they were discriminating against qualified female applicants.

Leaving aside complaints about “affirmative action for boys,” less attention has been focused on the social ramifications.

Thanks to simple laws of supply and demand, it is often the women who must assert themselves romantically or be left alone on Valentine’s Day, staring down a George Clooney movie over a half-empty pizza box.
“I was talking to a friend at a bar, and this girl just came up out of nowhere, grabbed him by the wrist, spun him around and took him out to the dance floor and started grinding,” said Kelly Lynch, a junior at North Carolina, recalling a recent experience.

Students interviewed here said they believed their mating rituals reflected those of college students anywhere. But many of them — men and women alike — said that the lopsided population tends to skew behavior.
“A lot of my friends will meet someone and go home for the night and just hope for the best the next morning,” Ms. Lynch said. “They’ll text them and say: ‘I had a great time. Want to hang out next week?’ And they don’t respond.”

Even worse, “Girls feel pressured to do more than they’re comfortable with, to lock it down,” Ms. Lynch said.