President Trump backed off his threat to close the border with Mexico, one day before he travels to California to highlight what he is calling an immigration crisis. “We’re going to give them a one-year warning,” Trump said Thursday, referring to Mexico. Trump said that if the flow of drugs and immigrants is not halted, he would then impose new tariffs on Mexican goods, targeting automobiles partly manufactured in Mexico. “If the drugs don’t stop — Mexico can stop 'em if they want — we’re going to tariff the cars. And if that doesn't work, we’re going to close the...