I've been told that islamic countries (and Muslim areas in India) tend to have high rape rates, and immigration from such countries tends to bring a few extra rapists. (Note: not trying to suggest all immigrants or all muslims are rapists.) Canada has more islamic immigration than the US, so this is a possible cause.

I haven't bothered to research the issue, so I'm happy to be corrected. A quick google search finds this source http://www.frontpagemag.com/readArticle.aspx?ARTID=6251 , along with a bunch of far less credible sources. Anyone have good information on this hypothesis?