The percentage of households that own homes hit a peak of almost 70% in 2004 and 2005. By the second quarter of this year, that slipped to 67.4%, according to the Census Bureau. Now, a University of Utah analysis projects it'll drop to about 63.5% by 2020 — the lowest since 1985.

"It will fall steadily by about half a point per year," says Arthur C. Nelson, director of the university's Metropolitan Research Center. "We'll have far more renters in the future."

Homeownership has long been viewed a key to building stable communities and middle-class families. Federal policy encouraged it with tax credits and government-backed mortgages. Now, demographic changes, strict mortgage rules, energy-saving policies and lessons learned in this housing crisis are driving more people to rent.

About 57% of the 30.3 million housing units added from 2005 to 2020 will be rentals, Nelson says.

"So many of our federal and state and local policies are driven by the assumption that homeownership is inherently preferred over renting," he says.

The housing collapse may have an impact.

"We're returning more to what was normal in the 1960s," says Dowell Myers, housing demographer at the University of Southern California. "People didn't buy homes then as an investment. They bought them to raise families."

Renting also may be more appealing because:

• Households are smaller. The youngest of 79 million Baby Boomers will turn 56 by 2020 and many will be empty nesters who favor small homes. The 20-something millennial generation is at a peak age for renting.

"What we used to think of as the typical American family — married couple with children — is really not typical anymore," says Mark Obrinsky, chief economist for the National Multi Housing Council in Washington, D.C.

•It's tougher to buy. The subprime mortgage crisis is tightening credit availability.

•Some arenew to the USA. Most recent immigrants rent.

•Somewant to save energy. From tax credits to mass transit, going green is reshaping growth.

Homeownership is not inherently good or bad, Obrinsky says. "Let's give people the best set of housing choices. They want to be a renter, let them be a renter. If they want to be an owner and they can afford to be, let them be an owner."