The New Orleans-based Dirty Dozen Brass Band celebrated its 40th anniversary in 2017.

The Dirty Dozen Brass Band’s 40th anniversary snuck up on co-founding trumpeter Gregory Davis.

“I didn’t really think about it at first,” Davis said recently. “It was like turning 50 — all of a sudden, you’re 50, and that’s it. Then 60 hits.

“I look back on it now, to see the different twists and turns it’s taken to get where it is. It’s almost unbelievable that we’re still here.”

The Dirty Dozen is still very much here, still one of New Orleans’ longest-running and most consistently successful bands. Their own considerable accomplishments aside — much-acclaimed albums for major labels, repeatedly touring the globe, collaborating with everyone from Widespread Panic to Elvis Costello — they are largely responsible for revitalizing the entire brass band genre.

On Saturday, the Dirty Dozen will headline the Joy Theater for a 40th anniversary celebration. Doors open at 8 p.m., show time is 9 p.m.; tickets are $40 to $75.

The “dozen dirty guests” slated to take part include the Preservation All-Stars, Anders Osborne, Ivan Neville, Benny Jones & the Treme Brass Band, "Big" Sam Williams, George Porter Jr., Walter “Wolfman” Washington, Alvin Ford and former Dirty Dozen drummer Terence Higgins. “We had more people that wanted to be included than we had time,” Davis said.

He did not set out to be a godfather to the brass band community. After graduating from St. Augustine High School and its famed Marching 100, Davis enrolled at Loyola University as a music education major. He figured he’d become a high school band director while playing funk and R&B on the side.

Though it’s hard to imagine now, as brass bands seemingly populate every club, wedding, festival and street corner, they were in short supply in the early 1970s. Jazz banjoist Danny Barker formed the Fairview Baptist Church Christian Band with the dual purpose of preserving brass band tradition and giving neighborhood boys a constructive creative outlet. Fairview's members included trumpeter Leroy Jones, who attended St. Aug with Davis.

Jones formed his own Hurricane Brass Band and recruited his pal Davis as one of its substitute players. Jones had also gotten Davis to join St. Aug’s brass band.

“That piqued my interest” in brass band music, Davis said. “With funk and R&B, being a trumpet player meant playing a line that lasted 30 seconds, then standing around playing tambourine for the next 10 minutes. That’s not that appealing. With brass bands, I saw an opportunity to play all the time.”

While still a Loyola student, he began rehearsing with an informal collection of like-minded musicians. They included baritone saxophonist Roger Lewis, trombonist Charles Joseph, his sousaphonist brother Kirk Joseph, and tenor saxophonist Kevin Harris. All but Charles Joseph are still active members of the Dirty Dozen Brass Band.

Their repertoire reached well beyond traditional brass band standards to include almost anything: modern jazz, funk, R&B, even TV theme music. “At gigs, we played what we played at rehearsals,” Davis said.

One early favorite was “Bongo Beep,” a bebop tune by Charlie Parker. During one funeral procession, Davis recalled, “the crowd enjoyed it so much that we played it 10 or 12 times. That was encouraging.”

Drummer Benny Jones had connections to the social aid and pleasure club community. That connection led to the nascent Dirty Dozen marching in Sunday afternoon second-line parades.

One of those parades ended at the Glass House, a small bar on South Saratoga Street between First and Second. The proprietors asked the Dirty Dozen to play an extra hour inside the bar following the parade. “Within that hour, they sold every ounce of everything they had,” Davis said.

Members of the social aid and pleasure club invited the band to return for its Monday evening meeting/party at the Glass House. The restocked bar was once again drained dry.

With that, a tradition was born. The Dirty Dozen at the Glass House on Mondays was the early ‘80s equivalent of the Rebirth Brass Band at the Maple Leaf Bar on Tuesdays: A weekly happening populated by both locals and in-the-know visitors.

At the Glass House, a $1 cover charge included a plate of red beans and rice. More than 200 revelers would squeeze in. The likes of Dizzy Gillespie, Jon Hendricks and members of Manhattan Transfer and the Red Hot Chili Peppers would drop by after their own gigs in town.

It wasn’t particularly lucrative; Davis remembers making $35 or so per man for four hours. “It was never about the money. It was about playing some music.”

The Dirty Dozen eventually signed with a national booking agency and started touring for weeks on end. They marched in second-line parades less frequently. The younger Rebirth took over the Monday night Glass House gig, even recording the 1991 album “Rebirth Kickin’ It Live!” there.

The Dirty Dozen’s own recorded catalog includes several ambitious projects. “Voodoo,” the Dozen’s 1987 major-label debut for Columbia Records, featured guest turns from Dizzy Gillespie, Dr. John and Branford Marsalis. For 1991’s “Open Up: Whatcha Gonna Do For the Rest of Your Life,” producer Scott Billington pushed the musicians to write more complex pieces; Davis composed a song suite.

“It was our first effort to create something other than just a song,” he said. “We took it as a personal challenge.”

They dazzled dancing crowds at clubs and festivals all over the world. Eventually they added a guitarist and swapped out their stand-alone snare and bass drums for a full drum kit. Their versatility led to recording projects and tours with the Black Crowes, Widespread Panic and other rock bands. During the 2017 Voodoo Experience in City Park, the Dirty Dozen’s horn section backed modern rock band The Killers on the main stage for three songs, including a cover of Fats Domino’s “Ain’t That A Shame.”

The Dozen has cut back on its touring schedule. “Doing 200 shows a year is not as exciting as it was in years one to 30,” Davis said. “We’re getting older, and we’re involved in other things. It didn’t make sense to be out there as much. But it’s still quite profitable.”

He proudly notes that he put his three children through Southern Methodist University, Spellman College and Stanford University without going into debt.

He has other pursuits. He books the Jazz Tent at the New Orleans Jazz and Heritage Festival, and hires entertainment for the Harrah’s casinos in New Orleans and Bossier City. But “the most enjoyable thing I still do is play gigs with the Dirty Dozen.”

Even after 40 years.

Follow Keith Spera on Twitter, @KeithSpera.

Keith Spera writes about music, culture and his kids.