Howard Zinn, an author, teacher and political activist whose leftist "A People's History of the United States" became a million-selling alternative to mainstream texts and a favorite of such celebrities as Bruce Springsteen and Ben Affleck, died Wednesday. He was 87. Zinn died of a heart attack in Santa Monica, Calif., daughter Myla Kabat-Zinn said. The historian was a resident of Auburndale, Mass. (snip) At a time when few politicians dared even call themselves liberal, "A People's History" told an openly left-wing story. Zinn charged Christopher Columbus and other explorers with genocide, picked apart presidents from Andrew Jackson to Franklin...