Wire is added to existing barrier infrastructure along the U.S.-Mexico border near Nogales, Ariz., on Feb. 4, 2019. (Robert Bushell/CBP) Pope Francis has donated funds of $500,000 to assist migrants ...

Migrant crossings at the U.S.–Mexico border have fallen to their lowest level in more than four decades — but the sharp decline has left thousands of migrants stranded in Mexico, where they are ...