Traditionally, there has been a significantly higher circumcision rate for Catholics than for others in the U.S. And it has been Catholic hospital policy as well, but no more so than with other hospitals. In other words, it has never been a Catholic religious "rule," although quite a few guys - even Catholic guys - think that's why they are cut.
Mexican Americans are getting cut, and getting their kids here cut as well. And it is practiced in Mexico too, but the rate is nowhere near that of the U.S.