ROMA-LOS SAENZ: The sun has barely set when Mexican traffickers inflate their boat, load 15 migrants on board, yelling at the kids to stop crying, and then row in a frenzy across the Rio Grande, landing on US soil in just a few minutes.

The same scene has been playing out almost daily for two months, sometimes right through the night. In the first half hour of darkness on Sunday, four inflatable boats with about 50 undocumented immigrants from Honduras and Guatemala arrived in Roma, Texas, almost simultaneously.

US agents from the Customs and Border Patrol (CBP) often converse and even exchange shouted jokes with smugglers on the Mexican side of the river, but do not try to stop them if they do not set foot on US soil.

When the migrants arrive -- at times in the hundreds, and many of them minors traveling alone -- there are sometimes no agents left on the river banks to process them.

The CBP agents will instead stop them half a mile away, at the end of a sandy trail that leads to this town of 11,000 in the Rio Grande Valley. Most migrants surrender voluntarily in the hopes of being granted asylum in the United States.