User blog comment:VonGlusenburg/Well any ideas?/@comment-1896940-20101006185120/@comment-461469-20101006185651

Bill, you are looking at it wrong: the US expands into Mexico, not Mexico expanding in the US.

That, on the other hand, is totally plausible, as Mexico could not stop the American's in the early 1900's in interfering in the Civil War and trying to capture Pancho Villa.