... are well-illustrated over at Paul Kedrosky's Infectious Greed. Dig this chart from his post.
The chart shows what would have happened had the Federal budget been held to just (just!) 4% annual growth starting in the year 2000. There would have been several years of surplus, the latest being about $17B in 2008.
In 2000, there was an already oversized Federal government with mammoth amounts of money for self-important politicians to play with and hand out to all kinds of groups. There was money for earmarks so they could have sent lots of pork home. Instead, they spent more and more and more, all while the party of fiscal sanity, the Republicans, was in control.
Now that the party of fiscal ignorance* and class warfare is in office, we're truly screwed. It didn't have to be this way.
* - Please, spare me your arguments that the Democrats are anything other than morons when it comes to money. I can think of trillions of counter-arguments.