There’s nothing particular naturally about national borders. But they are real. You probably don’t have a natural right to be anywhere on the globe absent plane travel, a heavily regulated industry subject to various national rules.
Everyone has the natural right. They’re just prevented from exercising that natural right by filth from various governments, including ours.
I will not lift a pinky to help enforce national borders. I won’t vote for scum like Donnie that threaten to enforce them more zealously. I won’t snitch on someone whom I know is in the US illegally. I won’t answer anything other than the legally required questions at internal checkpoints or show an iota of gratitude. Etc.
