US network CBS is hoping to revive its struggling news ratings with the debut of Evening News presenter Katie Couric.
Couric revived NBC's Today Show after joining in 1991
Couric, 49, became the first female solo presenter of a major network's evening news on Tuesday.
The newsreader, who previously fronted NBC's Today show, was signed by CBS as the long-term replacement for Dan Rather, who retired in 2005.
CBS hopes Couric will boost ratings among younger viewers, many of whom get their news from the web and cable TV.
Couric became one of the figureheads of US news broadcasting during her time with NBC, where she interviewed US presidents Bill Clinton and George Bush.
But she has drawn criticism for what some see as blurring the line between news and entertainment.
The news presenter has featured in films such as Shark Tale and Goldmember, as well as presenting the Tonight Show - a role usually taken by comedian Jay Leno.
The BBC's Jeremy Cooke, in New York, says Couric's appointment marks the end of a totally male dominated era.
Generations of Americans have grown up receiving their news from white middle class men, from Walter Cronkite to Peter Jennings, Tom Brokaw and Dan Rather.
Amid falling ratings, CBS has made a multi-million dollar gamble that Katie Couric can reverse the network's fortunes, our correspondent adds.
But given the fact that so many Americans now receive their news from alternative sources, it will be an uphill task, even for Katie Couric,