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Country music’s biggest stars are mostly working for free this week as the CMA Music Festival has the genre catering heavily to the brand’s ultra-core fans.

The Judds got the festival started June 10 with a 45-minute set at Riverfront Park, a site that was completely submerged when the Cumberland River flooded in early May. The duo attracted “one of the largest crowds ever at Riverfront,” said CMA chairman Steve Moore, setting the tone as a constant flow of acts takes over multiple stages through June 13.

Lady Antebellum, Carrie Underwood, Alan Jackson and Jason Aldean were among the stars at the first night’s LP Field stadium show, configured for 42,000 ticket holders. The venue was close to capacity: while some four-day passes remained, single-day tickets were sold out for Thursday through Saturday, and Sunday’s passes were close to gone, according to the CMA.

Brad Paisley, Rascal Flatts, Reba McEntire and Keith Urban are among the superstars set to play the stadium during the event, which is being shot for a Tim McGraw-hosted Sept. 1 ABC special, “CMA Music Festival: Country’s Night To Rock.”

The Riverfront stage, where admission is free, features 10 acts a day—including Clay Walker, Chris Young and Gretchen Wilson—while several other stages provide outlets for mostly developing talent.

Performers pack even more into their schedules by throwing fan club parties or signing autographs at the Nashville Convention Center. In the most visible example, aylor Swift plans to pen her name for 13 hours at Bridgestone Arena June 13.

It’s all designed to hyper-serve a fan base generally recognized as the most loyal of all genres.

“They’re the reason why we’re standing here right now,” Lady A’s Hillary Scott said before taking the stage at LP Field.

The CMA Fest is just one of numerous country events on the Nashville calendar during the week. Billboard led into the festival with the inaugural Billboard Country Music Summit, a two-day conference co-sponsored by the Country Music Assn.

And Kid Rock hosted the CMT Music Awards June 9. The show broke CMT viewing records to become its most-watched awards premiere, with a rating of 10.8 million total viewers, according to Nielsen Media Research. The show also ranked No. 1 among 18-49 cable viewers during its time slot.