MATAMOROS, MEXICO — On a recent Wednesday, Daniel Cortez, a 45-year-old mechanic from Honduras, and Richard Betancourt, a 46-year-old pipe fitter from Venezuela, were holding court at the migrants camp here on the northernmost edge of Mexico.
They sat in bridge chairs under a tarp and a drizzly, gray-white sky. Beyond the tents, past the field strewn wit…

