Regardless of who wins the election, the campaign of 2004 has already made history. For the first time, a cable news channel — Fox — attracted more viewers than a broadcast network when they were competing head to head, covering the Republican National Convention.

Was this a watershed for a new partisan journalism in America? I think the real meaning is something else.

What happened this summer, and particularly last week, is likely to be recalled as the end of the era of network news. At the very least, mark this as the moment when the networks abdicated their authority with the American public.

Should we care? Consider: The rise of network television news was arguably the most important development in American politics in the latter half of the 20th century. The arrival of news divisions in the 1950s and ’60s meant that for the first time citizens could regularly see events for themselves.

Within a remarkably short time, nearly everything about the way we elected our leaders changed. Presidential primaries became the means of nomination. Parties were weakened. Conventions became communications rather than decision-making events. The smoke-filled room all but disappeared.

We began to respond to different qualities in our leaders. Personal characteristics began to transcend resume. Policy, as James Carville notes, became a character issue. Party platforms were just pieces of paper. With the old ways of vetting candidates gone, the public started demanding that the press provide more personal information about its political leaders — not excluding their sex lives. Some say that the kind of people we elected changed.

The rise of the networks also helped raise the media to a position of unprecedented prestige. By the late 1960s, an anchorman, Walter Cronkite, was the most trusted man in America. Watching Cronkite, just back from Vietnam in 1968, declare the war unwinnable, President Johnson turned to an aide and said that if “we have lost Walter, we have lost the country.” A few weeks later, a majority of Americans polled were in opposition to the war. Johnson declined to run for reelection.

Networks were consequential — and serious in purpose. While newspaper people are loath to admit it, TV journalism at its best could tell stories more powerfully than print.

Now, with their decision to forgo any meaningful coverage of the conventions, the networks have signified — despite whatever rhetoric they offer — that the prestige and influence of their news divisions no longer matter much to them.

No wonder the public turned elsewhere. In effect, the networks’ owners have altered their brands. They have signaled that they are now almost entirely economic institutions. Certain news programs may remain important, such as NBC’s “Today” show, but only if they add to the bottom line.

The networks still air nightly newscasts that are often superb, and nearly 30 million Americans still watch. But the average age of their audience is close to 60, and now the network owners have done even more damage to these programs and the news divisions that produce them.

What difference will it make that the networks are ceding TV journalism to cable? Network news was built around the carefully written and edited story, produced by correspondents and vetted in advance to match words and pictures. On the network evening newscasts, 84 percent of the time is taken up by such packages, according to content analysis by the Project for Excellence in Journalism’s annual State of the News Media study.

Cable news is a live and extemporaneous medium built around talk. Only 11 percent of the time is devoted to edited stories. Eighty percent is given over to in-studio interviews, studio banter, “anchor reads” and live reporter stand-ups, in which correspondents talk off the top of their heads or from hasty notes.

What is lost in the cable obsession with “live” is the chance to double-check, to rewrite, to edit — and often to even report. What is lost with the passing of network TV, in other words, is the journalism of verification. It is gradually yielding place to a journalism of assertion.

There are subtler differences. Network journalism, built around visual storytelling, tends to take viewers to the events of the world outside. Cable news, built around talk-show hosts, tends to take viewers into the studio. In this new TV journalism, in a sense the news is secondary to the staged debate about the news.

Network journalism originally was designed not to make a profit but to create prestige. Cable is all about profit and keeping costs low. What is disappearing is an idealism about the potential of TV as a medium to better our politics and society.

After this summer, Americans will no longer see network news in quite the same way. The network owners may not fully understand this. Even if they do, there is little evidence that they care.