Well, what a read! I live in sleepy villita Marathon, and even locals could learn from your history essays. Boquillas del Carmen, Coahuilla, Mex., is open to US tourists now. You do need a passport. Just hold it up to the camera, leaving and entering the USA. You can take the boat, wade, or ride a burro up to the villita. The people there have things nicely organized now, you won't be pestered and will have good food, music, and cold beers at Falcon's bar. Ten years ago when US border hysteria had cut off the villagers from jobs, schooling, and groceries in the park, and almost all the men had left for work in the US, I organized, with motorcycle friends from Minnesota and locals here, a effort at re-opening the school down there. We got hundreds of boxes of books and school supplies sent down here, and waded to the middle of the river to give them to the residentes. The border patrol sat on their horses watching to see that we didn't step one foot over the middle of the knee-deep river... It is widely thought here that no big time doperas would use this incredibly harsh land to smuggle, if the US would not continually squeeze the life out of the border villages by denying access to them. For hundreds of years families have seen the river as joining rather than dividing us... Tourists can without fear visit this border land, and enjoy a day in Boquillas- it's been 20 years since the Acosta operation was broken up. Your hard work in documenting the old roads here is fantastic. I'll sure use your research when I travel along la frontera!