The Federal Communications Commission on Friday voted to phase in requirements that local TV stations put information about political advertising online.

Under the rules, TV stations affiliated with the four top TV networks in the nation's 50 largest markets will be required to file political information online first. All other TV stations will be exempt from the new requirements until July 1, 2014, to give the FCC the opportunity to see how the changes work.

The vote came as a rebuff to broadcast station owners, who had been lobbying vigorously against the change.

Though FCC rules already require broadcasters to document their political ad sales in publicly accessible files at their stations, you have to visit a station in person to get the data.

Under the new requirement, you can access in the information at the click of a mouse.

Broadcasters are expected to reap $3 billion from political ad sales this year, FCC Chairman Julius Genachowski said in an April 16 speech at the National Association of Broadcasters convention in Las Vegas.

The new rule adopted by the FCC also will require broadcasters to publish online other information that they currently keep in the public files in their stations, including network-affiliation agreements and contracts affecting station ownership.

"In putting these files online, the FCC is requiring broadcasters to take a step that innumerable other entities have opted for since the World Wide Web became a part of our daily lives, and putting public files on the Internet in 2012 makes sense," Commissioner Mignon L. Clyburn said in a statement. "It is the expected means of data viewing, and this action requires no unreasonable amount of production or disclosure."

He added: I see no reason to limit the reach of the online public file. We do not restrict, in any way, shape or form, who can access the existing paper files, and I see no need to do so for this new regime."

At a news conference after the vote, Genachowski rejected TV station arguments that the online revelations could hurt broadcasters financially.

“The record does not show that there’s any likelihood of … commercial harms coming out of this, because we’re talking about information that is already publicly available,” he said. “While it’s information that is difficult for an ordinary consumer to access, it’s not difficult for commercial businesses to access. So any existing commercial business that believes there’s value in those rates is already getting them.”