EL PASO, United States --- The United States bolted tough new immigration policies into place Friday, setting up an uncertain future for desperate migrants reaching its southern border, as a top official expressed confidence the system will hold. Thousands of people remained in Mexico hoping to enter the United States, as it was not yet clear how the stringent new rules for people crossing the border illegally would be enforced. In the Mexican border city of Ciudad Juarez, some 200 migrants were blocked by US troops from accessing Gate 42, the entry point to El Paso, Texas, where hundreds crossed on Thursday. In Brownsville, Texas, migrants who crossed before Friday were bei...Keep on reading: Thousands of migrants face tough new US border rules