Apologies for the agressive approach last time. Have read your posting from Homeland Security. Even if their higher number of 450,000 was correct, based on the 2007 information from the prisonstudies.org website (or at least the site that one now redirects to) from the original map posted, excluding those illegal immigrants would still give the USA a prison population rate of 608 per 100,000 of the total population. That would put the US into second place behind the Russian Federation on 611.

I still believe you need to look for other causes beyond illegal immigration for the true cause of the high US prison population. By blaming one issue alone you are oversimplifying the situation.