Mike Gross said:
The crossing at Boquillas had been unstaffed on either side at least since the early 1970's.
The same was true at Lajitas, where one could drive across the Río Grande at low water. Nancy Weaver and I did that one time in the midst of a group of kayakers coming down the river. A similar situation was true for the La Linda bridge, which surprisingly had a Mexican customs station but not one on the U. S. side. None of these great crossings are open anymore. See my Carbide Corner piece in Texas Caver Vol. 53, no. 3 (2007) for an exciting crossing after La Linda had closed. Mark Minton