A 116-band festival probably sounds like Coachella or Lollapalooza. But 59 different stages? For free? Its no wonder the town of Napa is trying to keep Porchfest under wraps.

The basic premise of the Porchfest concept, which was born in Ithaca, New York in 2007, is to showcase local music on people’s front porches and yards.

It’s proved wildly successful, and dozens of cities now hold their own Porchfests. But Napa was the first in the western U.S.

“The first year we all had butterflies in our stomach,” said Rachel Clark, who helped start Napa Porchfest in 2011.

“That morning we’re like ‘What if only 250 people show up?’  It ended up being more like 2,500,”Clark said, as she handed out maps to new arrivals wandering the streets of downtown Napa. Bikes zoomed by, families with strollers were out in force and lawns were dotted with strangers chatting and hopping from band to band.

This year, with music ranging from Celtic folk to hip-hop, and everything in between, attendance topped 12,000, despite an intentional lack of promotion outside the area. There’s a concerted effort to keep Porchfest focused on locals. To play here, at least one member of the band must live in Napa County, and even the food trucks have to be local.

“it’s a little more relaxing than our usual big shows where we’re in front of thousands of people,” said Izi Holokahi, who sings and plays ukulele for Blessed Love Gospel Reggae, a 10-piece band

He’s sweating in the 85-degree heat, minutes after finishing a set out in front of the keyboardist’s house.

“People here live right down the road from each other,"said Clark. "So at least they know now, whenever they walk or drive past this house, 'Hey man! That’s the guy that was in that reggae band!'

“Who knew that our retired judge [is] an amazing drummer in a band? And our local kindergarten teacher is an awesome vocalist!"

“I think it is absolutely the best thing this city has done,” said Sheree Solomon, who hosts an annual get-together every year. She and some friends are sitting on lawn chairs in her front yard, sipping wine and watching passers-by.

"It gets everybody together as a family," she said. "It supports all these local young startups. It’s awesome. …Every city should do this. It’s a family affair.“

Porchfest also can serve as a springboard for up-and-coming musicians, who need exposure and have limited venues in Napa County.

“It’s a great place to come and listen to music, and it doesn’t cost anything. So you can’t beat that," said Joe Barreca, who’s watching a band called Powerglide play on the porch of a house that dates from the late 1800s.

The home is being restored by Lauren Ackerman, to become a local heritage museum of sorts. But Ackerman’s plans hit a major speed bump when last year’s earthquake hit.

“All the walls fell down in the main part of the house,” she said while giving visitors an impromptu tour. “I was about 45 days from being done and had to basically lock it up and put the key away for about eight to nine months.”

The Porchfest planning committee had been urging Ackerman to participate for several years. Napa County Landmarks, a local nonprofit and the event’s fiscal sponsor, sees live performance as a way to bring the town’s beautiful old houses to life.

“The music changes everything,” says the organization's director, Stacey DeShazo. “We want people involved in historic preservation and saving our structures, and seeing these old houses in these great neighborhoods, but seeing it in a different light."

“We've done house tours for 30 or 40 years, and we do bicycle tours of historic neighborhoods, we do all kinds of ways," says Napa City Councilmember Juliana Inman, who is also chair of the Porchfest committee. "And this has by far been the most effective way to get lots of people into our historic neighborhoods and appreciate them.”

Inman has also helped other communities who are trying to start their own Porchfest, including the town of Carmel, Indiana.

Here in California, San Francisco’s Mission and Noe Valley neighborhoods held their inaugural Porchfest this year, and the town of Gilroy is holding their second one this September.