Had you checked the first google result for United States debt, you would have found where the confusion is coming from: the national debt is 14.5 trillion, and the total debt is 54 trillion (Source: http://www.usdebtclock.org/). I'm guessing "total debt" according to the debt clock includes things like state governments and private citizens, although Wikipedia claims that the 14.5 trillion figure is total debt (http://en.wikipedia.org/wiki/United_States_public_debt).