"Congo Square," a cross-cultural collaboration between trumpeter Wynton Marsalis' Jazz at Lincoln Center Orchestra and percussionist Yacub Addy's Odadaa! ensemble, takes its name from a historic site in New Orleans where slaves gathered for music-making and dancing.

"They were having a bad time," Marsalis said. "So they made sure they had a damn good time."

The 16-movement suite had its premiere last year in the Crescent City, Marsalis' hometown. Now the principals are taking their show on the road for an 11-city tour. They're hoping not only to entertain audiences, but to underscore "the Afro nature of American culture," Marsalis said during a recent phone interview.

"Congo Square" also sends a message of solidarity and hope to the people of New Orleans as they continue to rebuild after Hurricane Katrina.

"We had this tragedy, but you know what? We're still here, we still play our music and we still dance our dance," he said.

Marsalis, 45, lives in New York City these days, although he'll always have a soft spot for New Orleans.

"I'm a musician - I mean, how could I not?" he said.

"Congo Square" blends jazz and other American musical forms with the drum rhythms and bell patterns of traditional African music. The suite doesn't try to re-create the sounds of Congo Square in the 1700s and 1800s, although it does attempt to conjure a similar spirit.

"The piece is really festive," Marsalis said. "I thought of the Congo Square people ... working all week. They were coming to have a good time."

He pictured musicians and dancers kicking up their heels during the weekly jam sessions, while children frolicked.

"You know those days you never want to end?" Marsalis said. "That kind of day and that type of feeling, they had every week."

Look for the Jazz at Lincoln Center Orchestra and Addy's Odadaa! troupe to cut loose, too.

"We're all on the stage together," Marsalis said. "We go back and forth with each other. ... They're all dressed in their garb and they're dancing and they're singing, while we're playing and we're swinging.

"Yacub and them don't read music, so they improvise all the time. So do we."

Marsalis had been wanting to collaborate with Addy, a native of Ghana, for years. They first crossed paths in 1991, when Marsalis caught Odadaa! in concert.

"It was really unbelievable, man," Marsalis recalled. "They had me jumping out of my seat."

While composing "Congo Square," he was struck by the similarities between the music you might hear, say, during a New Orleans parade and the African musical traditions embraced by Addy and Odadaa!

"One of our main beats - boom, da boom, boom-boom, da boom, boom-boom - Yacub and them had a rhythm exactly like that," Marsalis said.

That groove throbs beneath "Ring Shout/Kolomshi," the first movement of "Congo Square."

A studio recording of the entire suite is due out in the fall, along with a completely different album pairing Marsalis with a far less obvious collaborator: Willie Nelson.

The country legend is "one of the coolest people on the planet" and "a great musician," Marsalis said.

"Willie has perfect pitch," Marsalis said. "We'll play some of the most obtuse introductions to a song like "Stardust,' and he'll come in exactly on the right note."

Apparently, they've gotten to know each other well enough for Marsalis to joke about the marijuana smoke aboard Nelson's tour bus.

"You just gotta put your goggles on and go up in there!" Marsalis said.