U2, which recently announced a stadium tour, had been informally discussing the possibility with Bonnaroo organizers for two or three years until the timing finally clicked in.

Although festival headliners in recent years have been mainstream rock and pop stars such as Billy Joel, Kanye West and Paul McCartney, Bonnaroo has always included a top jam-band attraction such as Dead and Company last year and My Morning Jacket in 2015.

Bonnaroo’s organizers say they don’t view the festival as tetd to Jerry Garcia guitar solos, and haven’t for many years.

“We certainly have jam-band roots from the first year, but our goal wasn’t to create a jam-band festival. The goal was always to create a great music festival,” says Ashley Capps, founder of AC Entertainment, Bonnaroo’s founding promoter.

Almost every Bonnaroo lineup in recent years has contained one prominent jam band, and the festival has taken pains to play up its all-star “Superjams,” which have included Derek Trucks, Dr. John and The Black Keys’ Dan Auerbach in recent years.

“Last year, for the first time, we had running water, we were able to put in showers and bathrooms.