I first crossed the U.S.-Mexico border in 1996, at 19 years old.

I took an airplane.

No passport required then, I presented my Texas Driver’s License at customs in Mexico City as documentation of my American citizenship. My purpose: to help run a day camp for the summer through a YMCA exchange program called Mano a Mano Sin Fronteras. Each day, I walked a mile from my host family’s apartment in the city center to the metro station, rose out of the subway system 40 minutes later to catch a bus that dropped me another mile-walk away from the community center in Naucalpan, an outlying barrio of the federal district, where I spent my days with Kristy and Luis, my peer volunteers, building a program from scratch.

For weeks I fought off back-to-back cases of dysentery as well as a buzzing terror that lived in my ribcage—everyone spoke Spanish…