Enough with this argument already. The term "American" has more than one meaning. The definitions from Merriam-Webster Online:
1 : an American Indian of No. America or So. America
2 : a native or inhabitant of No. America or So. America
3 : a citizen of the U.S.
4 : AMERICAN ENGLISH
Using the term in the more restrictive sense to refer only to those from the United States is perfectly acceptable.
Nice try, but how silly. The issue wasn't whether US Citizens are American, it's whether Mexicans are Americans. However, thank you for posting that definition. It's clear, I think you'll agree, that Mexicans ARE Americans. You guys may hate our neighbors, but I'll be damned if I'll let you pervert our language for your despicable and underhanded immigration agenda.