Economists Carmen Reinhart of the University of Maryland and Kenneth Rogoff of Harvard University have recently shown that a 90 percent debt-to-GDP ratio usually touches off a crisis.
This year, the debt will reach 63 percent of GDP, a ratio that has ignited crises in smaller wealthy nations. Fiscal crises gripped Canada, Denmark, Sweden, Finland and Ireland when their debts were below where the United States is shortly headed.
National debt seen heading for crisis level
The article doesn't address the medicare/medicaid/Obamacare/social security/Bush-drug-for-elderly unfunded mandates (which are at least 50 TRILLION and realistically are closer to 100 Trillion.