"We will see their migration rates swell even higher if the jobs become more plentiful," Frey said. "Families, older professionals and retirees will be latecomers; they have more financial baggage and will need to make more careful decisions about when and where to move."
Richard Florida, an American urban theorist and professor at the University of Toronto's Rotman School of Management, called the mobility gain an important sign the U.S. economy is getting back on track.
"Young people are moving out of their parents' basements and sampling places and sampling careers again," he said. "After living at home for a while, young people have kind of maxed it out. They are heading to bigger, vibrant cities, predominantly, because they're looking for economic opportunity and building their social networks."
About 1.7 percent of the U.S. population moved across state lines to a new home in the 12-month period ending March 2012, up slightly from 1.6 percent in the previous year.
The share of young adults ages 25-29 who moved to a new state was higher, about 3.8 percent. That's up from 3.4 percent in the previous year and the highest level since the height of the housing boom in 2005, when mobility was 5 percent. The 0.4 percentage point increase in 2012 is also the biggest jump for young adults since 1999, when the rapid rise of Internet startups and the need for young workers during the dot-com bubble drove migration.
Moving rates for college graduates of all ages remained mostly flat at 2 percent.
Among Americans 55 and older, out-of-state moves dipped from the previous year to a low of 0.7 percent. At the height of the housing boom, interstate migration for this group reached well over 1 percent, due mostly to baby boomers opting to retire early to residential hot spots in the South and West.