Not only that, but the border is literally the Rio Grand River for much of the length. Can't build a wall/fence in the river, or within a certain distance of the water, due to erosion concerns.
Posted By: Puget Ute
Date: Monday 7 January 2019, at 04:53 pm Recommended by
Also, the river is not straight everywhere and it meanders. Therefore a wall/fence would need to be built set back from the river, where it will mostly run through private property. Any right-of-way taken via Eminent Domain will necessarily split peoples' property and cut them off from the river side of their land.