For the 22nd time since taking over as Portland's mayor, Sam Adams this week found himself stepping off a plane in some other mayor's city, all so he could presumably spend the next couple of days telling everyone why the city that sent him—ours—is the bigger rock star.

This time, it was Detroit. Last week, it was Stockholm. Before then, it was Seattle, Toronto, Washington, DC, and Los Angeles. And that's only the itinerary since August.

Despite their frequency, the trips have hardly been controversial. Sometimes they lead to intriguing economic news, like the announcement that Target might explore adding a store downtown. In other cases, the results are quieter—helping businesses in Portland expand into new markets.

"Linking the Portland brand to Portland businesses, and having a strong ambassador for that in the mayor, adds an enormous amount of value to their pitches," says Noah Siegel, Adams' director of international affairs.

Adams, in fact, already has more frequent flier miles than his past two predecessors combined. But here's a question: Have you ever wondered how much all that salesmanship costs?

A review of the mayor's travel expenses since taking office, not including costs from two recent trips, shows nearly $14,000 in hotel rooms and flights billed to taxpayers, paid either from Adams' office budget, by the Portland Development Commission, or by the city's Office of Governmental Relations. Many of the city-funded trips are one-day affairs relying on red-eye flights.

But that's only the half of it—give or take. The majority of Adams' personal travel expenses, at least $16,000, have been picked up by private groups. That number will climb significantly once costs for recent trips, including Adams' visit to Stockholm, funded by the State Department, are tallied.

That's typically the model for private donations: The host or backer of the event that invited Adams pays his tab, like a sister city organization that sends him to Asia. But that hasn't always been the case.

At least twice, Travel Portland, the group the city pays big bucks to advertise Portland and plant favorable news stories in the New York Times, has subsidized Adams.

Once this year—according to the most recent reports tracking city officials' gifts—Adams' trip expenses were paid by the Port of Portland, an entity that does so much business with the city, it must register as an official lobbyist.

Are the trips worth the time and expense?

"He's traveling for different reasons," says Rob Sadowsky, executive director of the Bicycle Transportation Alliance, and a supporter of Adams' past trips to study and evangelize the bicycling culture.

Sadowsky said some might pooh-pooh Adams' trip to Detroit, a mission to discuss "best practices" in a city that isn't known for them.

"There are interesting things going on in Detroit, around transit and trail development," he says. "And there are things to learn about how to embrace inclusion and diversity. That's very important to Portland."