Here's a short article from the Economist that I think lays it out pretty well.
http://www.economist.com/blogs/daily...mericas_budgetThe elephant in the room
America's fiscal problem cannot be solved unless entitlements are tackled
THE Republicans want to cut "wasteful" spending; Barack Obama has proposed a spending freeze on discretionary items such as education and national parks. But the big items are the entitlement programmes—Social Security, Medicare and Medicaid—that are set to take up an ever larger part of the American budget. The chart shows the proportion of GDP spent on entitlements and interest, compared with the proportion of GDP that the government is expected to raise in the form of revenues. It originally appeared in USA Inc, an analysis of America's fiscal situation compiled by Mary Meeker for KPCB, a venture capital firm (best known as Kleiner Perkins). The data come from the Congressional Budget Office's "alternative fiscal scenario", which is based on today's underlying fiscal policy but also incorporates some widely expected changes, such as an increase in the threshold for the alternative minimum tax rate. As can be seen, entitlements and interest will absorb all government spending by 2025. But when the CBO did the same sums a decade ago, says Ms Meeker, the critical point was reached in 2060. In short, the fiscal position is deteriorating rapidly. Where then is the appetite for cutting entitlements or increasing taxes sharply?
It won't be possible to ignore this problem for much longer.
(I'm at work so I might not be able to respond to comments in a timely fashion. All apologies)