One of the most tenacious myths of the Great Recession is the idea that the downturn is some important sense caused by an oversupply of houses built up during the great boom. In fact, construction activity fell off the cliff in 2006 years before we started being plagued by mass unemployment. And as new Census data (PDF) confirms, America is substantially under-housed at this point:
This research defines a shared household as a household with at least one resident adult who is not enrolled in school and who is neither the householder, nor the spouse or cohabiting partner of the householder. In spring 2007, there were 19.7 million shared households. By spring 2010, the number of shared households had increased by 11.4 percent, while all households increased by only 1.3 percent. In 2010, shared households accounted for 18.7 percent of all households, up from 17.0 percent in 2007.
Translation—thanks to the recession, a growing share of the adult population can't afford its own place to live.
And note that this way of slicing the data probably understates the real level of recession-induced doubling-up by excluding full-time students and romantic partners from the calculation even though at the margin dollars and cents influence these decisions.