Along I-10, at points east and west of El Paso, there are stations manned by the Border Patrol that routinely stops vehicles, enters buses, and inspects trucks looking for illegals.
We were in our RV at a check point after leaving Padre Island just outside Brownsville. It is very intimidating. Border patrol agent had one hand on his holster and the other held a leash of a less then friendly German Shepard. He asked if he could come onboard. Of course, we said yes. He smiled and said “have a nice day folks” and waved us on.