San Diego, California (CNN) -- On a recent trip to Mexico City, I had barely made my way down the concourse and arrived at the immigration processing area when I got stumped. Signs pointed the way to two lines: one for "Mexicanos" ("Mexicans"), another for "Extranjeros" ("Foreigners.") I stood there for a few seconds, unsure of where to go. Growing up in Central California, I had been called a "Mexican" my entire life. It's ethnic shorthand in the same way that my friends in Boston refer to themselves as "Irish" or my friends in New York describe themselves as "Italian." Later, I settled on "Mexican-American."
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Ruben Navarrette: Long, troubled history divides Mexicans, Mexican-Americans
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He says many were forced to leave Mexico because of the lack of opportunities there
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Mexicans tend to fault those who left; they remind Mexicans of hard times, he says
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Navarrette says Mexican-Americans are caught between two worlds
So the minute that a U.S. official says anything the least bit critical of Mexico, you start hearing -- in the @placeholder press, and among the elites -- complaints about how the Americans are encroaching upon their neighbor's sovereignty.
And yet, for Mexico, the really challenging relationship is with the more than 35 million @placeholder living in the United States.