so don't try to send us back somewhere we're not even from. train horn blares. the next day, and a few more stops down the train line, deep into southern texas, and you find yourself even closer to the mexican border — the last frontier, some call it. alpine station is the jumping—off point to one of america's most remote national parks. we drive through a vista that feels straight out of a western. they call it big bend after a twist in the legendary river here that today separates the usa from mexico — the rio grande. this is the rio grande! welcome to the border!