One of the authors of those famous op-eds was Alexander Hamilton, a politician who also founded the New York Post because he wanted to influence politics during what is sometimes labeled the “party-press era.” The newspapers of the day were so explicitly aligned with parties that many of them advertised their allegiances on their nameplates. Several of these have survived into our time with relic-like titles, such as the Arkansas Democrat-Gazette of Little Rock and The Republican of Springfield, Mass. (Amusingly, the Herald-Whig of Illinois and the Cecil Whig of Maryland also continue to publish, though probably only a few of their readers recognize their partisan origin.)
As printing presses improved and paper became cheaper in the 1830s and 1840s, however, publishers saw that readers could provide a major source of revenue. The era of the party press evolved into the era of the penny press as a new generation of publications aimed to sell to the masses, which meant selling to readers of all political persuasions. Many papers maintained partisan commitments, but they became better known for sensational crime stories that drove newsstand sales. The invention of the telegraph also hastened the demise of partisan journalism because the wire services wanted as many newspapers as possible to buy their articles. They began to invent a mode of reporting that tried not to take sides.
By the first decades of the 20th century, many journalists spoke of objectivity in political reporting as an ethical obligation. A lot of them meant well. Yet the media of the day still had loud critics. Mostly they were liberals who thought the press was too conservative and favored Republicans. As New Deal liberalism became the country’s reigning ideology, however, this dynamic reversed. Meanwhile, at the dawn of the television era, the Federal Communications Commission adopted the so-called Fairness Doctrine, whose professed aim was to keep political bias out of broadcast news but whose effect was to tighten liberalism’s grip on the press. In 1955, William F. Buckley Jr. founded National Review in part because conservative ideas were missing from much of the media. Ever since, complaints about the liberal media have been a cornerstone of conservative politics.