The idea of a “border wall” is not a new one – Americans might be surprised to hear that Indigenous peoples thought of it first, and it was to keep Americans out! In July 1874, one of the British-Canadian border surveyors along the 49th parallel named Albany Featherstonhaugh encountered a group of Assiniboine and Sioux south of Wood Mountain. They queried him closely about the purpose of the survey. When he told them (somewhat disingenuously) it was NOT to prepare for a railway, Featherstonhaugh reported that they were relieved. But they were disappointed, he went on, that some sort of wall or continuous embankment was not to be set up across the plains, since they’d been led to believe that was what was coming. (David McCrady, Living with Strangers. Lincoln: University of Nebraska Press, 2006, 56). Given history, they’d probably have asked for a wall on the east, too.