MCALLEN, Texas — The sleepy-looking downtown of McAllen would give passersby no reason to believe it is the epicenter of a border surge that threatens to consume the Biden administration’s first months. A large converted nightclub space with blacked-out windows has been transformed into a resting spot for migrant families, 600 of which are released to the Catholic Charities organization every day. An armed security guard stands at the front doors, which are locked for the safety of the masses inside. Conditions back home in northern Central American countries have prompted multiple migration surges over the past decade. And while the U.S. government was hyperfocused on it under the Obama and Trump administrations, Sister Norma Seni Pimentel, executive director of the Catholic Charities humanitarian respite center, said they failed to address the push factors sufficiently....