US Federal Government debt has now topped $30 Trillion with a further $5 Trillion committed and that is without States & Munis debts. Many US Munis are on the brink of bankruptcy.
But IMO the biggest long term US debt that should be of critical concern to the US Citizen & tax Payer is "Unfunded Liabilities" (see bottom right of the Debt Clock) which now is over $160 Trillion and rising exponentially .
If this were to be a mega corporation , then it would be a penny stock or worse due to its unfunded liabilities alone!