C-Span executives said they hoped that its search filters would be up to the task. Mr. Lamb said, “You can see if politicians are saying one thing today, and 15 years ago were saying another thing.”

He added, “Journalists can feast on it.”

One of the Web site’s features, the Congressional Chronicle, shows which members of Congress have spoken on the House and Senate floors the most, and the least. Each senator and representative has a profile page. Using the data already available, some newspapers have written about particularly loquacious local lawmakers.

C-Span was established in 1979, but there are few recordings of its earliest years. Those “sort of went down the drain,” Mr. Browning said. But he does have about 10,000 hours of tapes from before 1987, and he will begin reformatting them for the Web soon. Those tapes include Ronald Reagan’s presidential campaign speeches and the Iran-Contra hearings.

In a tour of the site last week, Mr. Browning said the various uses of the archives were hard to predict. He found that a newly uploaded 1990 United Nations address by the Romanian president Ion Iliescu was quickly discovered and published by several Romanian bloggers.

While C-Span does not receive Nielsen ratings, a recent poll by Fairleigh Dickinson University found that 52 percent of voters said they watched it at least once in a while. The poll did not distinguish among C-Span’s three channels. The original one, C-Span, shows every House of Representatives session; C-Span2 does the same for the Senate; and C-Span3 shows committee hearings, briefings, conferences and other events.

The archives of all three channels have been mostly uploaded, but they can only be streamed. Mr. Browning said video downloads were on his agenda. Users can embed the videos on other Web sites and clip small sound bites for repeat viewing.