American newspapers redefined journalism after the Civil War by breaking away from the editorial and financial control of the Democratic and Republican parties. Smythe chronicles the rise of the New Journalism, where pegging newspaper sales to market forces was the cost of editorial independence. Successful papers in post-bellum America thrived by catering to a mass audience, which increased their circulations and raised their advertising revenues. Still active politically, independent editors now sought to influence their readers' opinions themselves rather than serve as conduits for the party line.