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."
@highlight
Ruben Navarrette: Long, troubled history divides Mexicans, Mexican-Americans
@highlight
He says many were forced to leave Mexico because of the lack of opportunities there
@highlight
Mexicans tend to fault those who left; they remind Mexicans of hard times, he says
@highlight
Navarrette says Mexican-Americans are caught between two worlds
Extranjeros
So I took my U.S. passport and got in the line for @placeholder.
Mexicans
Mexican
Mexicans
Mexican
Mexicans
Mexicans
Mexican
But for @placeholder, who think in terms of centuries, not minutes, the reminders are everywhere.
Mexicans
Mexican
Mexicans
Mexican
Mexicans
Mexicans
Mexican
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.
Mexican-American
And yet, for Mexico, the really challenging relationship is with the more than 35 million @placeholder living in the United States.
Mexicans
Mexican
Mexicans
Mexican
Mexicans
Mexicans
Mexican
Besides, we're aware that many of the elite @placeholder in the ruling class don't like us.
Mexicans
Mexican
Mexicans
Mexican
Mexicans
Mexicans
Mexican
They see us as a reminder of a humiliating defeat and look down on us as inferior stock that isn't sufficiently @placeholder.
Mexicans
Mexican
Mexicans
Mexican
Mexicans
Mexicans
Mexican
If at least some @placeholder aren't yet ready to forgive the United States for how it treated Mexico a century and a half ago, then they have to accept the fact that some Mexican-Americans still hold a grudge for how their family members were treated much more recently than that.