A group of about 2,000 migrants left Mexico's southern border Sunday hoping to reach the country's north and ultimately the United States. The development comes weeks before the U.S. presidential election, in which immigration has been a key issue. Some migrants, like Venezuelan Joel Zambrano, believe a new administration in the U.S. could put an end to asylum appointments through an online system called CBP One. "That is what makes us fearful. They say this could change because they...