The US is not outside of the norm in terms of its debt levels

Debt Figure 7 (1).pdf Download this file

There isn't a debt "crisis" in the US.  In response to the collapse of the housing bubble revenues declined, automatic stabilizers that kick in (like unemployment benefits, food stamps, etc.) and our tiny (but helpful nonetheless) stimulus.  Governments are supposed to run deficits during economic downturns to make up for the decline in private sector spending.

Here is a comparison of of nations by the Brookings Institute.