ARIVACA, Arizona — A few miles from this hard-baked borderlands hamlet northwest of Nogales, we’re trudging uphill through a rock-filled desert gully. Some scattered, empty plastic water jugs, scraps of clothing stuck in the thorny brush and, on the ground in front of us, an abandoned, crude stretcher fashioned from striplings lashed with rags confirm that we’re standing in a path well-traveled by cross-border migrants. Or, if you... More >>>