The elevator door slides open. A man and woman step in.As they ascend, the woman turns to the man and says, "Who pops into your mind when you think of Walter Cronkite?" The man doesn't even have to think. He opens his mouth, and out it comes. "God," he says.

Early last evening, Walter Cronkite donned his customary dark jacket, climbed into his anchor seat and read, for the last time, the CBS Evening News.Much was made of this. In Washington and other cities many people held Cronkite-watching parties. People talked about the end of an era. And some acted like it was the end of the world.

"I don't think anyone will ever have the impact on America Walter had," says biographer Merle Miller. "Because he was there. He told us it was happening. He explained it." Like the tree falling in the forest, if something happened and Walter didn't report it, did it really happen?

"I guess Dad is leaving us," says author Frances Fitzgerald excitedly. "Oh, this is an emotional reaction, and I hardly ever watch TV, but I think he's just a wonderful journalist. It's some kind of genius of personality."

"He's one of those people you never want to see retire," says Sen. John Glenn (D-Ohio), who got to know Cronkite "on the Cape" during his astronaut days.

"There's just no one on the horizon to replace that boy," says former astronaut Frank Borman, now president of Eastern Airlines.

"Walter Cronkite," intones ABC sportscaster Howard Cosell, "has a dimensional mind, an abiding concern. There's been no diminution of his abilities whatsoever. He'll continue to be the bench mark and guidepost for all news commentators. He's always sought to bring integrity to the medium of which he is a part." Well, you get the idea.

After almost 19 years as anchorman, Walter Cronkite has become "Uncle Walter," and what should have been a fairly standard semi-retirement became cause for national regret. A few years ago a poll found that he had become the most trusted man in America. His face is as familiar as those of the presidents he has interviewed.

"He's become our electronic Uncle Sam," says author Kurt Vonnegut Jr.

Cronkite was there when John Kennedy died, and fought to control his tears as he read the bulletin. At the Democratic Convention in Chicago in 1968, he watched floor correspondent Dan Rather being roughed up by security guards, and was sufficiently disturbed to remark, "I think we've got a bunch of things here, Dan," Everyone remembers that.

"I remember when LBJ, during his more paranoid days, turned to an aide and said, 'I think Walter Cronkite is a Communist,'" says Miller, a Johnson biographer. "The aide said, 'Mr. President, I'm sure Walter Cronkite is not a Communist.' 'Well,' said Johnson, 'he keeps asking me these questions to embarass me, and I think the Communists are putting him up to it.'

"Walter Cronkite a Communist!" says Miller. "Good Lord!"

"It's like losing an old friend," groans writer Ward Just, a self-described news freak. "I lived up in Vermont for seven years. Up there, CBS was the only channel we got. I watched Walter every night. When I moved down to Boston, I started watching someone else, just for a change." It wasn't the same. "Walter Cronkite is the real goods," says Just. "There's nothing fake about him."

"I don't think it will ever again be like, 'Oh Christ, I missed Walter,'" says Miller. "Now we'll just wait until 7:30 and catch the educational network's news."

Of course, all through the long goodbye, Cronkite's friends, and his network, have stressed that last night's farewell wasn't supposed to be a funeral, even if some, the other networks in particular, were treating it as a multi-media memorial service. "I thought Mr. Cronkite was alive and well," critic Michael Arlen remarks drily.

Memorial or not, no one pretends it will be the same.

"CBS will continue to bring him out for august occasions," says Vonnegut, "and he'll still be our Uncle Walter. But he's the last of that romantic tradition, the last one with printer's ink in his veins. I guess the new ones will have electrons."

"He wasn't afraid to show his emotions," says Glenn. "Some newscasters try to maintain such supercontrol that they become part of the scenery. Not Walter."

Cronkite was the nation's man at NASA. "He loved that stuff," says Glenn. "He was just facinated by it all. I remember that vividly. He was entranced with it, not so much the technical side of it, but the exploration."

"He remains," Vonnegut wrote recently in The Nation, "as entranced by the unfolding of each day's news as a child with a new kaleidoscope."

"Remember Sputnik?" says Miller. "The Russians got theirs up first, and everyone thought that America was going down the drain: then we got ours up, and it was really like Walter was getting the thing up, because he was telling us all about it."

It is Cronkite who is remembered for blurting "Go Baby Go!" over the nation's airwaves as Apollo 11 lifted off the moon.

Annie Glenn, the senator's wife, first got to know Cronkite during the space shot. She waited out her husband's five-hour heavenly orbit at their home in Arlington. The Glenns don't live in Arlington anymore, and Mrs. Glenn doesn't like to say which network she watched, but she has fond memories of Cronkite.

"She found him very gentle, and very attentive," says an aide to the senator. "Mrs. Glenn had a severe stutter then. Over the years she has classified people -- those who were patient and willing to wait until she got things out, and those who weren't. For her, Walter clearly falls into the first category. He was special."

Cosell, who still sees Cronkite regularly, gets reverential when he waxes nostalgic over him.

"I remember an AFTRA [American Federation of Television and Radio Artists] strike. I was with ABC, and I was wearing a sandwich board on the picket line. I made myself very unpopular with my employer. I went to Walter for advice," says Cosell. "And he said to me, 'Howard, stick to your guns.'" That's what Cosell did. "And I got fined more than any person in the union.

"The other night at a dinner," Cosell continues, "Walter gave a hell of a speech about freedom of the press, directed toward the secretary of state, who was also on the dais. Walter," Cosell says with a flourish, "isn't afraid of anything.