Debra Johnson points us to the relative dearth of recent household formations.

She has a nice graph:







The graph illustrates an important change; after a secular decline in average household size in the US (from about 3.5 people per households after World War II to around 2.6 now), households are getting (slightly) larger. This matters for housing demand, of course, because households are the source of such demand (recent event have taught us that not a whole lot of people can afford to own more than one home). It is important to note that this change happened before the current economic calamity.

She does have some good news, though: age induced household formations should be rising over the next three years. The question is whether there will be sufficient numbers of jobs for young adults to leave the family nest on schedule.