CIUDAD HIDALGO, Mexico (AP) — Despite Mexican efforts to stop them at the border, a growing throng of Central American migrants resumed their advance toward the U.S. border early Sunday in southern Mexico. Their numbers swelled to about 5,000 overnight and at first light they set out walking toward the Mexican town of Tapachula, 10 abreast in a line stretching approximately a mile (1.5 kilometers). It was not immediately clear where the additional travelers had materialized from since about 2,000 gathered on the Mexican side Saturday night. They seemed likely to be people who had been waiting on the bridge...