Really? He had to go back almost a century to link the Democratic Party in the U.S. to racism? 

Did he bother to go forward some 40 years to when Lyndon Johnson signed the U.S. Civil Rights Act which he acknowledged would wreck the Democratic Party in the South, yet went ahead with it because he felt it was the right thing to do?

Or (jumping forwards a few years) did he bother to talk about Richard Nixon's "Southern Strategy" and how today most of the South (or at least the "white" part of it) is solidly Republican?

From your description, it doesn't sound like a very useful book.