In the seventeenth, eighteenth, and nineteenth centuries, as the invaders crept mile by mile across the continent, they drew the borders closed behind them, like ashamed ne’er-do-wells drawing curtains on their misdeeds. They built forts that served as borderland security, demonstrating and insisting on their control: they would remain and expel any who were here before them, and any—depending on their race and provenance—who came after them.
Exactly! People who benefit from an open border eventually want to retain that benefit by closing it behind them. And that is why you can find lots and lots of immigrants supporting closed borders. Because open borders dissipate benefits which citizens and residents wish to retain.
