I am reading the book Deeply Divided, Racial Politics and Social Movements in Postwar America, by Doug McAdam and Karina Kloos, 2014, Oxford University Press.
The book is a historical overview of political polarization in the US since the beginning of the 20th Century. It argues that the moderate and unpolarized politics from the end of WW2 to the 1980s is an aberration, and that racism has gotten much worse since President Obama came into office.
The book contains a depressing summary of what we already know to be true about right-wing extremism and how it is subverting political equality and the will of the people. However, it is useful to have this history in detail and to understand what is happening. Ignorance is worse than knowing the truth.
Same guy; more opinionated.