Follow PBS NewsHour’s complete coverage of U.S. news, reports and analysis.

After weeks of speculation and debate, David Letterman announced Monday he had agreed to stay on CBS for another five years. The move ends efforts by ABC to woo the late-night talk show host to their network.

It's the electronic version of an old-fashioned newspaper circulation war, with the nation's three all-news cable channels locked in a competition for viewers. Terence Smith surveys the battle lines.