JP Filo, CBS Broadcasting Inc. Pittsburgh Mayor Luke Ravenstahl talks with David Letterman during this afternoon's taping of "The Late Show," scheduled to air tonight. Click photo for larger image. Listen in After arriving in New York, Luke Ravenstahl talks about the bittersweet experience of becoming the mayor of Pittsburgh. Related content Transcript of press conference at New York City Hall by mayors Luke Ravenstahl and Michael Bloomberg

NEW YORK -- A mostly deferential David Letterman saved the zinger for last when he hosted 26-year-old Pittsburgh Mayor Luke Ravenstahl on "The Late Show," taped this afternoon for broadcast later tonight.

After asking Mr. Ravenstahl about Pittsburgh and about how he became mayor, and whether he'd "done anything to keep Ben Roethlisberger off a motorcycle," Mr. Letterman deadpanned:

"An appearance like this -- does it interfere with your homework?"

Mr. Ravenstahl was the first guest in this evening's taping and spent about five minutes on stage. Earlier in the show, Mr. Letterman remarked that when he was 26, he was still holding down a paper route.

The appearance on "The Late Show" was one of two stops Mr. Ravenstahl made in New York. His first appearance was to participate in a press conference at New York City Hall with Mayor Michael Bloomberg, at which they signed a statement endorsing the principles of the nationwide Mayors Coalition Against Illegal Guns.

Mr. Ravenstahl opened his visit on Letterman's "The Late Show" by extending best wishes to the family of the late Mayor Bob O'Connor.

It was a bittersweet day for Mr. Ravenstahl -- he got to go on a national comedy show watched by millions to promote his city, just two weeks after Mr. O'Connor's passing.

Mr. Ravenstahl, who flew this morning to New York City to appear on the show, said he would not have gone without the blessing of Mr. O'Connor's wife, Judy. The appearance caps a week of national attention for Mr. Ravenstahl, who became the country's youngest big-city mayor when Mr. O'Connor died after a two-month hospitalization for cancer.

"I had mixed emotions on whether it was appropriate to do something like this," Mr. Ravenstahl said this morning, while waiting for his flight at Pittsburgh International Airport. "I consulted with the O'Connor family and Bob's wife Judy, and spoke with her, and she gave me her blessing. Bob was the city's biggest cheerleader and would have loved the opportunity to tell the story of Pittsburgh."

The New York Times ran a front-page story on Mr. Ravenstahl Saturday, leading to the call from Mr. Letterman's producers. He was also interviewed by CNN. GQ magazine may be doing its own story.

The young mayor was joking about all the attention this morning, as Allegheny County police officers walked him and his wife Erin to his airport gate.

"Any chance I get to do the national stuff, I plan on doing, for the simple reason that it gives me an opportunity as the mayor to tell Pittsburgh's story, to change the national image. We're not the old smoky city that we used to be. And I think that's important. I think on the national level that [perception] is still there, and anything I can do to change it is certainly an opportunity that I won't pass up," he said.

Mr. Ravenstahl -- who was in line to take the mayor's job as City Council president -- was ready for joking with Mr. Letterman too, as well as other things. He was the placekicker for his college team at Washington & Jefferson and thought about packing some athletic shoes, should the sports-obsessed host tee up a football.

"I lot of people around Pittsburgh have had a lot of advice [about interacting with Mr. Letterman] but I'm just going to try to be myself, roll with the punches and hopefully have a little fun with it, but I'm sure he'll be himself and try to trip me up.

"I'd be more than happy to go out in the alley and try a few kicks, but we'll have to wait and see. I haven't [practiced]. We'll have to wait and see how that goes, if I do it."

In addition to his wife and the city's press spokesman, Mr. Ravenstahl is attending the show with a friend from grade school in Observatory Hill who now lives in New Jersey. Back in Pittsburgh, friends and family are throwing a Letterman party.

"Late Show" audience members waiting in the rain to get into the Ed Sullivan Theater this afternoon, most of them tourists, had never heard of Mr. Ravenstahl.

"I guess we'd rather see someone famous. Maybe he'll talk about the Steelers ... I heard The Who's going to be on. I'm probably more interested in that," said Steve Branca of Rochester, Minn.

"I don't know who he is," said Scott Jackson, 25, of Salt Lake City, Utah. "I probably prefer someone else, though."