NEW YORK – For more than 60 years, TV stations have broadcast news, sports and entertainment for free and made their money by showing commercials. That might not work much longer.

The business model is unraveling at ABC, CBS, NBC and Fox and the local stations that carry the networks' programming. Cable TV and the Web have fractured the audience for free TV and siphoned its ad dollars. The recession has squeezed advertising further, forcing broadcasters to accelerate their push for new revenue to pay for programming.

That will play out in living rooms across the country. The changes could mean higher cable or satellite TV bills, as the networks and local stations squeeze more fees from pay-TV providers such as Comcast and DirecTV for the right to show broadcast TV channels in their lineups. The networks might even ditch free broadcast signals in the next few years. Instead, they could operate as cable channels — a move that could spell the end of free TV as Americans have known it since the 1940s.

"Good programing is expensive," Rupert Murdoch, whose News Corp. owns Fox, told a shareholder meeting this fall. "It can no longer be supported solely by advertising revenues."

Fox is pursuing its strategy in public, warning that its broadcasts — including college football bowl games — could go dark Friday for subscribers of Time Warner Cable, unless the pay-TV operator gives Fox higher fees. For its part, Time Warner Cable is asking customers whether it should "roll over" or "get tough" in negotiations.

The future of free TV also could be altered as the biggest pay-TV provider, Comcast Corp., prepares to take control of NBC. Comcast has not signaled plans to end NBC's free broadcasts. But Jeff Zucker, who runs NBC and its sister cable channels such as CNBC and Bravo, told investors this month that "the cable model is just superior to the broadcast model."