From this:

If Arnold Schwarzenegger had migrated to Mexico instead of the United States, he couldn't be a governor. If Argentina native Sergio Villanueva, firefighter hero of the Sept. 11 attacks, had moved to Tecate instead of New York, he wouldn't have been allowed on the force.

Even as Mexico presses the United States to grant unrestricted citizenship to millions of undocumented Mexican migrants, its officials at times calling U.S. policies "xenophobic," Mexico places daunting limitations on anyone born outside its territory.

In the United States, only two posts - the presidency and vice presidency - are reserved for the native born.

In Mexico, non-natives are banned from those and thousands of other jobs, even if they are legal, naturalized citizens.

Foreign-born Mexicans can't hold seats in either house of the congress. They're also banned from state legislatures, the Supreme Court and all governorships. Many states ban foreign-born Mexicans from spots on town councils. And Mexico's Constitution reserves almost all federal posts, and any position in the military and merchant marine, for "native-born Mexicans."

Recently the Mexican government has gone even further. Since at least 2003, it has encouraged cities to ban non-natives from such local jobs as firefighters, police and judges...

Bear in mind that those being discussed above are naturalized citizens of Mexico who were born in other countries, not foreign citizens and not illegal aliens.