Dan Cubbedge's life has entailed several moves in his 23 years.

After moving a lot as a child, Cubbedge said he went to high school in California, left home at 15, and at 18 went first to Portland, Ore., Cheyenne and most recently, Casper.

He had to make friends in all those places, but typically spent the first several weeks alone.

This lonely fate is shared by many 20- and 30-somethings in the U.S., according to Frances Goldscheider, a professor and the director of the Population Studies and Training Center at Brown University.

There are roughly 86 million unmarried and single adults, according to the American Association of Single People. The number has been steadily increasing over the past few decades.

Goldscheider attributes this growth in single Americans to several things, including an ever-increasing age of marriage in the U.S.

For example, a study of Americans ages 25-29 showed that in 1970, 19 percent of men had never married, compared to 63 percent of men in that group in 2000.

The numbers also increased for women of that age group, jumping from 11 percent who had never married in 1970 to 46 percent in 2000.

"This is really a revolution in young adulthood," Goldscheider said. "Adult life no longer begins with marriage."

What's more, there has been a societal switch in the past century that meant an increase in the number of young adults who did not live at home with their families. Starting around the 1980s, those who did still live at home were often eyed with some suspicion, she said.

"That's when you began to see articles about the 'Peter Pan Complex' in magazines and books," she said. "It was a huge change from the early 20th century when, until you married, it was normal to live with your parents."

In the Western states, there are even fewer adults who still live at home.

"In the Mountain West, there's lower population density," Goldscheider explained. "If your parents have good job in a small town, the chance that their children will find one there, too, is unlikely. It's much different than a larger place like New York City."