you can't ever definitively say any state is "most corrupt." something like that is hard to measure in any objective sense and any methodology you come up with inevitably will have its critics.
take this article arguing that north dakota is the most corrupt state in the union. the article measures corruption by looking at convictions per capita. that gives a huge disadvantage to underpopulated states. it's not surprising that empty states like north dakota and alaska are at the top of their ratings.
the rankings also penalize states that aggressively prosecute their officials. (a point noted in the article). thus a state where officials regularly accept bribes but the prosecutors look the other way would register as less corrupt than a place with fewer bribe-takers but a more zealous prosecution. i suspect that most people would view the former as being more corrupt than the latter.
and why does it matter anyway? on monday robert grant, head of the FBI office in chicago, famously said, "If [Illinois] isn't the most corrupt state in the United States it's certainly one hell of a competitor." he was making a rhetorical point, i don't think he was trying to start a nationwide competition.
