Americans as a nation have no savings- the rate has been declining in recent years until last year, when it actually went negative.
The reason for this decline? Pundits have put forth a number of reasons, from credit card debt, and excess consumer spending, to a reliance on increasing home equity for savings. It is likely that all of these are contributing factors.
A Wall Street Journal article today by Jonathan Clements gives another reason- it seems that Americans are spending an inordinate amount on housing and transportation.