Millions of people wouldn't believe that President Kennedy had been shot, or that men were on the moon, until they heard it from Walter Cronkite.
No one person in news will probably have that kind of audience and authority again. There are almost a dozen different national TV news operations now, plus radio, Internet sites and citizen journalists who blog and tweet in real time, and often with real attitude.
If the moon landing happened in today's media landscape, you might have one network trumpet the accomplishment as a triumph for the American way of life. Another might say: Impressive, yes, but a victory for the crew-cut military-industrial complex that sucks money for shock-and-awe adventures from social welfare programs.
And bloggers might bleat: It was all staged on a set in Roswell, New Mexico.
Cronkite was a great broadcaster. He spoke to masses, not niches. He grasped that when the news was urgent, people would turn to the broadcaster not only for information, but for sincerity and calm.
Millions of people felt better to hear from this man who seemed experienced, but not jaded. He had a visible sense of grief in tragedies, and a little boy's delight in the glory of space shots. He had gray hair and hound-dog bags under his eyes, but ageless sincerity.
And, he was a great performer. You don't radiate reliability, hour after hour, night after night, without possessing a great actor's gift for staying in character.
Cronkite was acclaimed for being unflappable. But the moments he is being remembered for today are those where he let a small flap up on his feelings.
The slick of tears when he removed his glasses to note the time of John F. Kennedy's death. His gravelly, rock-solid voice breaking with excitement when two men took the first steps on the moon.
Today, so much of the media doesn't try to reach a mass audience, with all its unpredictable diversity and variations. They look for like-minded people who want a view of the news that will reassure them that they're right — that "that's the way it is." But in the welter of news sources, whom will they trust to tell them when it's not?