I’m not a historian but I would have thought that open borders were the norm not that long ago. I would guess that immigration restrictions wouldn’t have starte

I’m not a historian but I would have thought that open borders were the norm not that long ago. I would guess that immigration restrictions wouldn’t have started to be commonplace until at least industrialization. But regardless if that is right or not, siblings have pointed out that open borders are in fact common-place in many parts of the world today, e.g. EU and USA’s internal borders are open. And (as sibling has also pointed out) historic precedent or existing examples are not necessary to justify any belief. Abolishing slavery did not need a historic precedent, neither did gay rights, and theoretically neither does open borders.