Alt-funk rockers 311 don’t have to be too concerned with how well each new album does on the charts nowadays, even though the band’s latest, Mosaic, reached No. 6 on the Billboard 200. Like Jimmy Buffett and the Grateful Dead, they now have a cult following that is a community unto itself. Every two years, the faithful come together for 311 Day, which was inaugurated in 2000 and took place for the first time in Las Vegas in 2010. This year, 311 Day actually takes place during two consecutive days at Park Theater inside Monte Carlo Resort and Casino, complete with pre- and after-parties.

This year 311 also celebrates the 25th anniversary of their major label debut Music, the 1993 album featuring set staples “Freak Out” and “Do You Right.” They might just play the entire album during the marathon 311 Day concerts to the ecstatic delight of several audiences populated by several generations of fans for whom 311 continues to provide the soundtrack to their daily lives. Back in 1993, the Oklahoma-bred band was often considered in the context of their influences such as the Red Hot Chili Peppers, Faith No More and Bad Brains, sometimes taking critical flack for coming off as derivative.

311 addressed the criticism directly on “Come Original” from the 1999 album Soundsystem. By that time, they had been together for nearly a decade, having formed in Omaha when funk rock was peaking. Singer-guitarist Nick Hexum, guitarist Tim Mahoney, drummer Chad Sexton and bassist Aaron “P-Nut” Wills got together in 1990, becoming a quintet when they added DJ and singer Doug “S.A.” Martinez. Named after the Omaha Police Department’s code for indecent exposure, the group signed with Capricorn Records after moving to Los Angeles, and set about distinguishing itself with high-energy performances.

The ’90s were good to 311. The band’s self-titled 1995 album garnered hit single “Down,” and 1997’s Transistor included “Beautiful Disaster,” which Billboard magazine cited as their finest moment. By the end of the decade they had influenced a wave of rap-rock bands such as Crazy Town and Limp Bizkit, who came to the fore during the four years between Transistor and Soundsystem. By the time 311 made its “comeback,” the fan base was substantial enough to warrant a special observation of the bond between band and audience. The first 311 Day was scheduled in New Orleans on the 11th day of the third month of 2000, and a tradition was started.

The celebration was eventually relocated to Las Vegas and expended to two days. This year’s concert is preceded on Friday, March 9, by an 8 p.m. fan party at PRB Rock Bar at Miracle Mile Shops inside Planet Hollywood Resort. Saturday and Sunday’s concerts will be followed by after-parties at Double Barrel Roadhouse next door to the Park Theater. The band has its own 311 Amber Ale and an ale named for “Beautiful Disaster” that it plans to make available at all 311 venues. It’s another way to make a special connection with the fans, many of whom consider every day a 311 Day.

Park Theater at Monte Carlo 7:30 p.m. March 10-11, sold out. 844.600.7275