Hardly the world’s longest unguarded border. Anyway, the Canadian-US Border is effectively guarded. Where there are no humans, there is radar and electronic and air and satellite surveillance. If you cross into Montana, for example, somebody somewhere will know about it. Whether or not they initiate pursuit is the question. God forbid if someone brought in some Cuban cigars or filled a prescription at a fraction of US cost. And then we have to protect ourselves from all those poorly educated, poverty stricken, Molson-swilling Canucks clamoring to get in to pursue a better life and healthcare. And that bloody aggressive military—gotta watch out for them.
Sudan’s borders are a total of 4,200 mi. and there is no way they can guard them effectively. But they don’t have to. People are trying to get out, not get in. If a rich country like Sweden can’t effectively guard their borders, no way can poor old Sudan—and I believe there are even longer unguarded borders in the world.