I worked with guy from El Paso, and he told me that there is (was?) this badly designed turn off to Mexico and there was no way to turn around. You had to make the U turn in Mexico!
So quite a lot of people ended up unwillingly in Mexico!
Probably several ended up in Mexican jail!!!
My info is like 10 years old, maybe they fixed it?!
Yeah, those federales are pretty strict when it comes to enforcing their immigration laws - at least when someone is headed south.
Regards,