I listen to Texas news on the radio. The news about the wall say Trump is going to use eminent domain to take American's property to build the wal, so it will be built on IS property. Of course, the government has to pay property owners for the land. However, I see photos of Americans using the river for canoeing and fishing. If there is a wall there, it will be difficult to take your canoe over the wall. In some cases, like in the Big Bend National Park, it will be impossible. This wall seems like a "loser" for the US. Besides, sometimes, the river changes course.