Hi June, I'm home dear.  Where's Wally and Beaver?

A half-century slide in the number of people living under one roof has ended and has even reversed in some places, according to 2010 Census data released today.

Average household size is inching up in Florida (2.48 persons per household vs. 2.46 in 2000) and has stopped declining in Tennessee (2.48), according to the first wave of detailed data on 12 states and the District of Columbia.

The change was most dramatic for renters: The average household size in rentals rose or stayed flat in 11 of the states from 2000 to 2010. The biggest increases are in Florida and Tennessee.

Just as growing affluence let many Americans live with fewer people, the recession, high unemployment and the housing bust now are forcing some people to double up.

“The economy played a large role,” says Zhenchao Qian, sociology professor at Ohio State University who is doing research for the US 2010 Census Project, which studies trends in American society.

That’s why an increasing number of young adults are living with their parents — including “boomerang kids” who return after college. The percentage of young adults ages 19 to 29 who are living with their parents rose from 25% in 1980 to 34% in the late 2000s, Qian’s research shows.

“Young adults have poor job prospects when the economy is bad,” he says.

There is less of a rush to the altar as a result, which cuts the creation of households — a factor for planners and home builders.

The rapid growth in immigrants also affects household size, says William Frey, demographer at the Brookings Institution. Many embrace living with in-laws and family even after they marry, and others are forced into those arrangements because of cost.

Other highlights.

•Getting older. The median age (half older, half younger) in Maine is 42.7 — the highest of any state released so far. All the states showed declines in the number of people ages 35 to 44 and gains among those ages 45 to 74.

The oldest of 77 million Baby Boomers turn 65 this year and that generation is driving the aging in most states, says Kenneth Johnson, demographer at the Carsey Institute at the University of New Hampshire.

The share of people older than 65 in Florida actually dropped even though the median age rose from 38.7 to 40.7.

“We really are seeing the lull before the storm of the Baby Boom,” Johnson says.

•Fewer traditional households. All 12 states and the District of Columbia showed drops in the share of married-with-children families. The number of married couples who have no children rose in every state, in part because millions of Baby Boomers became empty nesters.

“Overall, it’s clear that non-family households are gaining more than family households, and households without children are growing faster than those with children,”.