Octavia_Melody, I'm not necessarily disagreeing with you, but what you posted almost sounds like something someone says just to make a point, perhaps without thinking about backing it up.
Aside from racists, which we still have, and who are still fighting diversity, please provide a few examples of how "Americans" (which is a pretty broad category) fought to stop diversity 75 years ago, which would be in the mid-1940's. I'll be open minded, since I'm no expert on American cultural mores from that time period.