In the classical-liberal age of 19th-century Europe, there were no immigration controls. Here is how Gustav Stolper — a German economist, classical liberal, and an immigrant — described the world he had known: This economic and social system of Europe [before 1914] was predicated on a few axiomatic principles. These principles were considered safe and unshakable…. They were freedom of movement for men, for goods, and for money. Everyone could leave his country when he wanted and travel or migrate wherever he pleased without a passport. The only European country that demanded passports (not...