I hate to say it...
But bigotry really has nothing to do with it. In some areas of the U.S., you might as well be in Mexico, including language, Mexican flags, and--this IMO is what makes it bad--outright hostility toward the rest of American culture and insistence that assimilation work in their direction. Some of these places are within a short drive of me.
Turn it around. Try to imagine entire neighborhoods in Mexico City where American flags flew, English was spoken, and the inhabitants insisted on English being on Mexican election materials.