These Truths: A History of the United States

by Jill Lepore

Entrenched partisanship in cable news eroded the institutions of democratic deliberation. The rise of cable news accelerated the polarization first of Congress and then of the electorate. During the reign of broadcast television, between 1950 and 1980, when there were only three major networks, ABC, CBS, and NBC, polarization was the lowest it had ever been, both before and since. Cable news made voters more partisan, by reinforcing their views and limiting their exposure to other views, but cable television had another effect, too: when the only channels on television were ABC, CBS, and NBC, and each network broadcast the news at 6:30 p.m., people who weren’t particularly interested in politics, who tended to be moderates, had usually watched, and, as a result, they’d tended to vote.