Border Towns

Dan Barry: EL PASO

At the foot of a bridge that helps bind El Paso and Ciudad Juárez, a United States Border Patrol officer warns two pedestrians not to stray once they reach the Mexican city. Stay on the main road. Avoid side streets. Very, very dangerous city. O.K.?

The pedestrians nod and join the back-and-forth human flow between one of the safest cities in the United States and one of the most violent in the world — getting worse by the month. Including a pause to take in the Rio Grande, here just a muddy stream with a boastful name, their walk takes five minutes.