In 1925, Adolf Hitler wrote in Mein Kampf:

"I know people do not like to hear this; but anything more thoughtless, more harebrained than our present-day citizenship laws scarcely exists. There is today one state in which at least a weak beginning toward a better conception is noticeable. Of course, it is not our model German Republic, but the American Union, in which an effort is made to consult reason at least partially. By refusing immigration on principle to elements in poor health, by simply excluding certain races from naturalization, it professes in slow beginnings a view which is peculiar to the folkish state concept. The folkish state divides its inhabitants into three classes: citizens, subjects, and foreigners."