In his first two weeks in office, the city's new mayor announced changes to his staff, readied a budget proposal, attended a handful of news conferences — and laughed it up on the "Late Show with David Letterman."

It's been a full schedule for the Pittsburgh native and standout high school quarterback who graduated from college just four years ago.

At 26, Luke Ravenstahl became the youngest mayor in a major U.S. city on Sept. 1, hours after his 61-year-old predecessor, Bob O'Connor, died of a rare brain cancer. Many believe the new mayor can finally help the city shed old stereotypes about smoke-spitting steel mills and a graying population.

"I think that having a youthful mayor ... is going to help communicate to the rest of the world that this is a place for people to raise young families. It's a place where dreams come true," said Andrew E. Masich, president and CEO of the Senator John Heinz Pittsburgh Regional History Center.

Ravenstahl's ascension caps a year in which the city has twice relished the national spotlight: first when its beloved Steelers won their fifth Super Bowl title and then when Major League Baseball's All-Star game was played here.

Yet underneath those bright moments, trends that reinforce Pittsburgh's Rust Belt reputation have continued. For instance, Pittsburgh's elderly population has been rising. About 14.6 percent of the city's population of 320,000 is over 65, compared with a national average of 12.1 percent.

It's a problem the young mayor knows firsthand — several of his own friends have moved away — and wants to address.

Ravensthal said he would like the city to try and retain more of the 50,000 college students that come to Pittsburgh each year to attend the city's universities. Though he doesn't have firm plans yet, his ideas include creating more internship opportunities at corporations in town and establishing a youth commission to get the views of younger people heard.

"It's our challenge as a government to help do whatever it is we can to make sure those folks stay here after graduation," said Ravensthal, who admits he doesn't have an iPod but did put a computer in his office, a first for a Pittsburgh mayor.

Jared L. Cohon, president of Carnegie Mellon University, where 90 percent of the students come from outside of the area, said students there have taken notice of Ravenstahl. "They like the fact that he's so young. I've talked to some of them and they think it's kind of cool," Cohon said.

Because of his age, Ravenstahl has already made a difference. Not many Pittsburgh mayors have been on national talk shows.

Letterman wasted little time in ribbing the youthful politician during a show this week. "An appearance like this," he asked, "does it interfere with your homework?"

One of Ravenstahl's first acts as mayor was attending the launch of a new promotional campaign for the region titled "Pittsburgh. Imagine what you can do here." It emphasizes the city as a hub for high-tech companies and medical research. The smoking steel mills that once lined its rivers have been replaced by two world-class sports stadiums, a state-of-the-art convention center and retail developments.

"He's a very tangible sign of what's good about the region and it's a great way to change people's perception about this region ... of being old and traditional," said Michele Fabrizi, president and chief executive officer of advertising and marketing company Marc USA and an architect of the campaign.

Ravenstahl grew up in the city and graduated in 1998 from North Catholic High School. As his school's quarterback, he led the team to a 10-1 record in 1997.

He went on to play football at Washington and Jefferson College, where he earned a bachelor's degree in business administration He followed his family into public service. His father is a district judge and his grandfather is a retired former state representative.

Ravenstahl became the youngest member of City Council at age 23, and the youngest City Council president in December. Before entering public life, the darked-haired Ravenstahl worked briefly in sales. His wife, Erin, is a beautician.

The city charter is unclear about how long he will serve — an issue that could ultimately be decided by the courts — but Ravenstahl said he intends to run whenever that election is held.

"I think he's a very astute young man and a very able person," said Ken Gormley, a Duquesne University law professor and former mayor of suburban Forest Hills. "But anyone walking into this job has a daunting task."