Figures released by the government, using as optimistic assumptions as one can reasonably imagine, project that government debt held by entities outside the United States Government will equal the entire Gross Domestic Product of this country in only 19 years. After that point is reached, the debt is projected to exponentially increase until it our national debt for the Federal Government alone is about three times our annual earnings.
The assumptions made to calculate the figures may be too optimistic becasue they assume that interest rates will remain at current levels- in fact those rates are just coming off 23 year lows and are likely to get higher as our debt/income ratio increases. They also assumed that government spending would be held to only the level of increase in the gross domestic product. In other words, government would not grow itself faster than earnings grow. Recent explosions in entitlement programs, such as the President's 400 billion a year in unfunded liabilities via the "Prescription Drug Program", guarantee that real government spending increases will be greater.
The figures also appear to exclued certain substantial debt that our government accountants also magically whisk away "off budget", as well as the "Social Security Trust Fund" that is really just a stack of IOU's held by the government backed by nothing but its ability to increase your tax burden.