This book shows how left-wing politics has shaped life in the USA, from the 1900s to the present day. Only the American right has ever really recognised the potency of the American left. Now, Rhodri Jeffreys-Jones fully details the left's numerous achievements, including the welfare state, opposing militarism, reshaping of American culture, black rights and civil liberties, awakening the USA to the dangers of fascism and great public enterprises such as the late Twin Towers. Jones tells the full story of the USA's left wing: how the socialists of the Old Left gave way by the 1960s to the anti-war militants of the New Left, and how they in turn gave way to a 'Newer Left' that advocated causes such as LGBT rights and multiculturalism. Bringing the discussion into the 21st century, he shows how the post-2000 Bush administration succumbed to the 'socialist' nationalisation it despised, and hails Barack Obama as a president for the left. It looks at why the USA's left is always underestimated: the relative absence of a free press, its tendency to deny its own existence, and the fallacious claim that if the right is always wrong, it must be wrong about the left's impact too. It explores the changes that have taken place in the years between the orthodox socialist challenge of a century ago and the actions of those President Obama describes as 'my friends on the left'. It draws on interviews with participants on the left including: Todd Gitlin, president of Students for a Democratic Society in the 1960s; Frances Piven, anti-poverty campaigner and bete noir of the American right; Bernie Sanders, socialist US Senator from Vermont; and, Marilyn Young, leading New Left historian of US foreign policy.