Roots had a tremendous impact not just on blacks but also on whites. I have a personal recollection about the impact of that series. About a week or two after the series was shown, the Ku Klux Klan came to town and were planning on marching downtown. A small group of lefties planned on a nonviolent counterdemonstration. The actual turnout was a shock to me. People came out in droves, both whites and blacks. Each Klan member found himself surrounded by about twenty or thirty anti-Klan locals. It was a glorious day. The Klan hasn't been back since. I can't help but think that the series Roots played a role in the large anti-Klan turnout.
Unfortunately, in the vast wasteland that is television, series like Roots are the exception rather than the rule but just think of the possibilities if it wasn't. Imagine . . .