How old is our great civilization, the US of A?

My friend, Chris, sent me this tid-bit this morning...Chris is a right thinking chap, and I think sent this to me as some type of blast on Obama, but all of the free money craziness that is going on today is under Bushie. But no matter which way you lean, you'll find this quote appropriate in light of what's going on in Washington...

"When the original thirteen states adopted the US Constitution in 1787, Alexander Tyler, a Scottish history professor at the University of Edinburgh, made the following comments about the fall of the Athenian Republic:

• a democracy is always temporary in nature; it simply cannot exist as a permanent form of government
• a democracy will continue to exist up until the time that voters discover they can vote themselves generous gifts from the public treasury
• from that moment on, the majority always vote for the candidates who promise the most benefits from the public treasury, with the result that every democracy will finally collapse due to loose fiscal policy, which is always followed by a dictatorship
• the average age of the world's greatest civilizations from the beginning of history, has been about 200 years"

So when did the US start getting great? In 1787? After the Civil War? After WWII?