Even if it might be the case that incarceration rates don’t necessarily correlate with corruption, they do necessarily reflect the extent to which a given nation’s government is (by means of its laws and its enforcement of those laws) at war against its own population; and, so, technically speaking, incarceration rates (the percentage of the population who are in prison) are supposed to reflect the prevalence of law-breaking within a given nation.
After all, by definition, people are presumed to be in prison for law-breaking, irrespective of whether the given nation’s laws are just — and if they’re not just, then this fact reflects even more strongly that the nation itself is corrupt. So, a high incarceration rate does strongly tend to go along with a nation’s being highly corrupt, in more than merely a technical sense — it’s almost more like being the definitive measure of “corruption.” So, the correlation between incarceration rates and corruption must be assumed to be high, and any measure of corruption which fails to at least include countries’ incarceration rates should be rejected.
Out of the world’s 223 countries, the U.S. has the world’s second-highest incarceration rate: 698 per 100,000, just behind #1 Seychelles, with 799 per 100,000. Seychelles doesn’t even have as many as 100,000 people (but only 90,024 — as many people as are in the city of Temple, Texas). By contrast, the U.S. has 322,369,319; so, the U.S. is surely the global leader in imprisonment. And, furthermore, #3, St. Kitts and Nevis, with an incarceration rate of 607 per 100,000, has only 54,961 people (as many people as are in the city of Columbus, Indiana). The only other country that might actually be close to the U.S. in imprisoning its own people is North Korea, which could even beat out the U.S. there, but wouldn’t likely beat tiny Seychelles: North Korea is estimated to have “600-800 people incarcerated per 100,000,” and a total population of “24,895,000.”