No, they're not the Mexicans. But our neighbors to the north--the Canadians.
https://qz.com/988951/the-us-is-finally-telling-the-public-who-overstays-their-visas-the-most-and-its-not-mexicans/?utm_source=YPL&yptr=yahoo https://qz.com/988951/the-us-is-finally-telling-the-public-who-overstays-their-visas-the-most-and-its-not-mexicans/?utm_source=YPL&yptr=yahoo