My initial instinct is to say "George Bush II", his Iraqi disaster and the drainage of resources and intelligence from the United States. But---

I think that Katrina in New Orleans was IT for now. We had a major city destroyed by nature, and that destruction was enhanced by stupid, greedy human decisions over the last 50 years at least (plenty of blame to go around!) This also demonstrated our apparent inability to keep people out of harm's way even with a couple of days notice, our total inability to rescue them immediately after the disaster, the incompetence of our government, the ignorance and lack of education in our general population, the terrible violence that emerged when law enforcement disappeared.

The destruction of wetlands and incredibly costly engineering of the Mississippi river are continuing, making the whole area just as dangerous as before.

I could go on and on about that one....sorry. Just finished reading the latest James Lee Burke novel set in the aftermath. Riveting.