Reddit mentions of American Progressivism: A Reader

Echoing the sentiments already said-- Sanders is a politician, not an intellectual.

In terms of book recommendations, I always recommend Jonathan Haidt's The Righteous Mind, which goes into the moral foundations of liberals and conservatives, and can help you see things from another perspective.

In terms of liberal book recommendations, one book I really liked was American Progressivism: A Reader. It's a collection of speeches, essays, and letters written by progressives in the Progressive Era, and really gets at the core of what it means to be progressive, in a way that is not actually articulated all that much in modern times.

It also serves as a sort of history lesson, as a lot of the programs advocated for in the various speeches and essays were later adopted, forming the foundation of the American welfare state that exists today; hence you can see the thought behind these programs when they were first discussed.

General

• The Righteous Mind - OP, if you only choose one book, it's gotta be this one. Trust me.
  
• The Fractured Republic - Written by a committed conservative, but very fair. Critical of his own side and empathetic of the positive traits on the left. Also one of the best writers in political history/theory imo.
  
  Conservative - I'm keenly interested in the intellectual history of American Conservatism and could make this this list could go on forever. I'll keep it to three, but if you want more suggestions feel free to ask.
  
  
• 10 Conservative Principles - Not a book, but essential to understanding conservatism
  
• Conservatism in America Since 1930 - A reader that guides you along a chronological and ideological path of conservatism in America.
  
• Hillbilly Elegy - Less academic, but very well written and explains the support of Trump from the rural white working class perfectly
  
  Liberal - You may get a better liberal reading list from another user, but I'll give it a shot.
  
  
• On Liberty - Modern political dialog from the left still echos Mill's classic defense of cultural liberty. A must read for all Americans.
  
• American Progressivism: A Reader - As you can tell, I'm a big fan of reading political giants in their own words.
  
• The Affluent Society - The controversial classic that underpins progressive economic policy.