[mthom]

What do you make of the poll that said 60% of Mexicans believe both that the southwest of the US really belongs to mexico and because of that they feel they can come at will to the US legally or illegally?

[Clemenza]

Mexican textbooks teach that the SW was "stolen" from Mexico. It should be no surprise that 60% of first generation immigrants or those living in Mexico believe it to be true.
Even that doesn't amount to separatism, any more than the neoconfedarates in the south.