There was Senator Joe McCarthy- that was a shameful period of American history- with the US polity mirroring that of Stalin's Russia in staging show trials of intellectuals- but McCarthy got run out of town eventually.
And then there was Vietnam.
There's nothing the Bush administration has done- waging disastrous imperial wars, corrupting the political life of the Republic- that hasn't been done before- and worse. America has these massive mood swings- and when she turns nasty the rest of the world cowers- but she always pulls herself right in the end.
I'm not an American, I'm not even particularly Americanophile, but I believe as a sober matter of fact that the USA is the single best political idea we (meaning human beings) have ever had. A Republic based on the values of the Enlightenment- how cool is that!
Of course America has done horrible things- which nation hasn't?- but she remains- because of the vision of her founding fathers- "the last best hope of earth".
That's a quote from Abraham Lincoln- the nearest the dirty profession of politics has ever come to producing a saint.
So, happy birthday, America,
You'll get over these recent set-backs-
Of course you will.