In the late 1960s, Janis Joplin went on tour with a novel opening act that caused just as much buzz as her own show.

It was a rock band with a horn section, and it called itself the Chicago Transit Authority. Later, when the real transit authority objected, the name was shortened to just Chicago.

"I remember being backstage with Janis, with her bottle of Hennessy (cognac)," said Chicago trombonist and arranger Jimmy Pankow.

"She befriended us. Janis was disenchanted with her own people on the tour because they were all yes-men," Pankow said. "She hung with us on the road, because we treated her like an equal."

Still on the road after more than four decades, and fresh from an appearance on the Grammy Awards telecast in January, Chicago plays Tuesday at Santa Rosa's Wells Fargo Center for the Arts.

"This month, it's 47 years we've been doing this, and trying to get it right," Pankow said with a laugh, speaking by phone from his Nashville home.

With more than 100 million records sold, including 21 top-10 singles, Chicago clearly has done something right.

"When we were sitting at a keyboard writing these songs, and putting our personal angst on tape," Pankow said, the musicians didn't know the songs would be embraced by several generations to come.

Over time, Chicago's hits, including "If You Leave Me Now," "25 or 6 to 4" and "Does Anybody Really Know What Time It Is?," have become classics.

"We're dumbfounded at the fact that these songs, that started with these personal feelings, have become part of the fabric of so many lives," Pankow said.

"We look out in the audience, and whatever song we play, we see people re-experiencing the moment that song represents in their lives," he said.

That includes songs Pankow composed for the band, including "Make Me Smile" and "Colour My World."

"People still come up to me and say, 'Colour My World' is the song we danced to at our wedding," he said.

Despite its long history and rich song catalog, Chicago continues to write and play new music.

"It's not all oldies-but-goodies," Pankow promised.

The band's roster has turned over many times, but like singer and keyboardist Bobby Lamm, Pankow has been with Chicago since the beginning in 1967.

"When we started out, man, we were renegades. We treated the horns like a main character in our music," Pankow said. "People said, 'Rock 'n' roll with horns? What the hell is that?' Radio stations did not even understand our stuff."

The band was playing the nightclub circuit in the Midwest, covering tunes by the Four Tops and the Temptations, when the musicians decided to head West and try to make it big with their own music.

"So we went to California, with a prayer and a lot of guts and high hopes," said Pankow, now 66. "We were just a bunch of young kids."

But soon they got some high-powered help.

"We played at the Whiskey A Go Go on Sunset Strip, and that's where Jimi Hendrix heard us," Pankow recalled. "He came back to the dressing room and said, 'Do you want to go on the road?' So we opened for Jimi Hendrix on tour, which was exposure for us that was priceless. We were unknown, but he took us on the road, and so did Janis Joplin."

It wasn't long before record companies took notice, with competitors bidding to sign a contract with the band. Within months, Chicago the band was in New York the city, recording its first album.

"Simon and Garfunkel were in the studio — Studio A at Columbia Records — all day," Pankow said, "and we had the night shift, because we were the new kids. I remember walking up to that microphone and being scared."

As we know now, young Pankow needn't have worried.

"Never would we have guessed that after 47 years, we'd not only be still busy, but busier and more in demand than ever," he said.

You can reach Staff Writer Dan Taylor at 521-5243 or dan.taylor@pressdemocrat.com. See his ARTS blog at arts.blogs.pressdemocrat.com.