In just two decades between 1891 and 1910, about 12.5 million people immigrated to the United States. The majority of these immigrants came from the countries and states that composed Eastern Europe, among them Austria-Hungary, Poland, and Russia. But the people leaving these countries did not necessarily claim ancestry in them. The borders of nations during the nineteenth century in Eastern Europe changed so frequently that immigration from eastern and central Europe cannot be accurately divided up into nationality counts. As Russia and Austria-Hungary expanded their empires, taking over many smaller countries, countries like Poland that had existed for centuries disappeared as sovereign (self-ruling) nations. Many ethnic groups besides the Poles found themselves without a state: the Lithuanians, the Czechs and Slovaks, the Croatians, and the Slovenians were all displaced (involuntarily removed from their home) at one time or another. In the twentieth century, the Russian...