David Letterman's extraordinary stamp on comedy and New York, the city the "Late Show" calls home, will endure long after he bids farewell tonight.
From his breakthrough following Johnny Carson's "Tonight Show" on NBC in the 1980s, to his more than two decades as the face of CBS' late-night programming, Letterman changed the landscape by bringing a modern, distinctly New York take to the news and celebrity.
"He is the foundation and predecessor of Jon Stewart, Stephen Colbert and John Oliver; that off the cuff, no holds barred style of presentation," said Paul Levinson, a professor of communication and media studies at Fordham University.
Levinson said Letterman, 68, was savvy enough to understand that his generation loved the traditional, scripted variety of comedy but also wanted something more -- an improvisational approach to the talk show. Viewers tuned in because they never knew what they might see -- a fight between Andy Kaufman and Jerry Lawler, for example, or Drew Barrymore flashing the host.
"Letterman from the beginning, even though he did a lot of planning, he was almost doing this off the top of his head," Levinson said.
The host kept New York at the fore of his programming, even though the show targeted a national audience. The risk of doing this was significant, especially during the earlier years of his run, when New York went through tough times, according to Ron Simon, the curator at the Paley Center for Media.
"New York, and the team of writers here, brought a harsher look at the absurdity of life," he said. "New York can inspire that; it's not a casual type of humor. It creates the craziness."
Other late-night hosts who also call New York home have paid tribute over the past week. Jon Stewart hailed Letterman as an "incredible epiphany of how a talk show, or how entertainment, or how television could be."
"To be an innovator and have that longevity? Damn, the list is David," Stewart said.
Jimmy Fallon, who brought the "Tonight Show" back to the Big Apple last year, recalled Letterman's emotional monologue during his first show after the 9/11 attacks.
"David Letterman is courageous," Fallon said on his show.
Experts don't know what to expect when Stephen Colbert takes over the Ed Sullivan Theater in September, except that he'd surely continue the tradition of re-thinking the norms of late night.
"He knows there is something artificial about creating a show. He will play off the conventions of a talk show," Simon said.