The best way to understand how far the U.S. has drifted from its original design is to listen to Ron Paul. He sounds like Thomas Jefferson would if he were around, which makes him a flake and a radical to most of today's Republicans and Democrats. But he strikes a chord with a surprisingly wide range of good people, from techies who want to be left alone, to college kids who don't want to support their selfish boomer parents for the next thirty years, to soldiers appalled by what they're being asked to do.
"Classical liberal" concepts like individual freedom, limited government and non-interventionism aren't a factor in today's politics because they conflict with the goals of both the left and right. But post-crash they'll be in the mix. In the meantime, we've got Ron Paul to keep the pot boiling. Here's an interview with PBS's Judy Woodruff in 2007.