During this time, “old-stock” Americans had very strong ideas about race. They held a very narrow view of which people were racially pure. They also tended to hold Social Darwinist ideas about competition between what they saw as the races.
These people did not see race in terms of black and white. Instead, they tended to feel that people like Italians and Greeks and Eastern Europeans were not truly white. These new immigrants were seen as occupying a level below the “old-stock,” but certainly above people like African Americans. The “old-stock” felt that it was important for them to maintain racial fitness so that they could continue to prevail in what they saw as a Darwinistic battle for supremacy with the new immigrants.