When Hitler published Mein Kampf in 1924, he held up a foreign law as a model for his program of racial purification: The U.S. Immigration Restriction Act of 1924, which prohibited the immigration of those with hereditary illnesses and entire ethnic groups. When the Nazis took power in 1933, they installed a program of eugenics--the attempted "improvement" of the population through forced sterilization and marriage controls--that consciously drew...