It depends on what you use to measure.
Retail corruption? US is one of the least corrupt countries in the world. Almost everywhere else, except Canada and certain parts of western Europe, retail bribes of police and local bureaucrats are simply the way things are done. Yes, it does happen here, and when people get caught, it makes news. South of the Rio Grande, South of the Alps, East of the Oder River, and west of the Sea of Japan? It's like speeding - technically a crime, but only enforced for reasons other than stopping the crime.
Influence peddling/corporate influence? Much more prevalent than retail corruption, but the same caveat - EVERY OTHER COUNTRY works closely with, and has a tight relationship with, it's domestic corporations. Germany treats Siemens special because, well, Siemens is German. In the US we must treat all companies the same, so GE should get bupkiss. When they don't, it makes news.
Foreign Corrupt Practices Act: This ones a winner. We are the only country that prosecutes people for actions that are *legal* in other countries.
One reason we seem corrupt when we look at ourselves is that we expect so much more from ourselves and our government. I think in general that's a good thing. But the risk is that, with so many high horses being ridden, it only takes a few to fall beforer a moral panic ensues and we start making even more bad law.