An estimated 1,600 tickets had been sold before 6 p.m., for Saturday's "Inside the Walls" concert featuring Wynonna Judd and The Big Noise, with three other bands preceding her 8 p.m. appearance.
One of those attending was Reice Flowers, 8, who was attending her first-ever concert.
A country music fan, she was looking forward to Wynonna's appearance, "all the fun" she was going to have and "that I get to stay up late!"
Thomas Miller, of Fulton, drove to Jefferson City for the "unique" concert on the former prison's grounds.
"We did it last year, even though it rained," he told the News Tribune. "I thought it was a pretty good value."
Dylan McCord, of Columbia, provided the sound for Saturday's concert.
"I've been doing this a long time, so none of it's really that hard - providing I have appropriate power and the gear that's requested," he said. "My primary goal is making sure the band is having an experience that allows them to play comfortably for the crowd.
"Once I've done that, the rest of it's really easy. If they look and sound like they're having fun, the crowd will have fun."
He said the prison buildings' stone walls add a variable not usually found inside a concert hall, but doesn't make his work more-complicated.
Last year's concert featured Travis Tritt, and attracted nearly 2,500 people in spite of the rain.
"We've been really blessed with this beautiful, sun-shiny day," Jefferson City Mayor Carrie Tergin said. "It's a perfect day to be in prison.
"Who would have thought that a prison is such a perfect venue for music?"
Laura Schrimpf, of Jefferson City, told the News Tribune she came to the prison because, "I like live music and I've never seen Wynonna. It's close to my house, so I thought it would be fun."
Although the final numbers won't be known until later in the week, Jill Snodgrass, who organizes the concert as part of the larger "Salute to America" celebration, predicted a "full house" for the evening's concert.
"It's really community celebration," Snodgrass said.
Tergin and Snodgrass were pleased this year's prison concert had attracted more sponsors - including the Missouri Lottery and Holts Summit-based Champs Chicken.
"I think that's really a sign that people are talking about this concert, in this very unique, special event that's like none other, anywhere," Tergin said.
Schrimpf hopes organizers will continue the "Inside the Walls" concerts.
"I think it's really cool to do events like this, in old, historic places."
Miller also hopes there will be more in-prison concerts.
"I'll come back, without a doubt," he said. "I enjoy it."
Tergin would like to see other concerts in the prison venue.
Snodgrass said for now there's a reason to keep it tied to the Independence Day celebrations - money raised by the "Inside the Walls" concert goes to the Salute to America Foundation and to "important prison restoration projects."
She added, because most of the "Salute to America" events are free to the public, "As it grows and we get 70,000 people who come - we have to be able to provide the infrastructure aspect of it.
"So, the idea of (this concert) allows us to generate additional funds that we're able to turn right back around into 'Salute to America,' to make it bigger and better."
The Prison Brews restaurant's barbecue dinner was sold out at 250 tickets, and was served inside "A" Hall, the cell building erected in 1868 that remains as the oldest building in the former Missouri State Penitentiary complex.
Dinner was served in 25-minute shifts - similar to the period allowed for inmates to eat a meal in a working prison.
More than 200 volunteers helped concertgoers into the prison and get food and drinks that were available.
There also was a noticeable law enforcement presence on the prison grounds and in the streets outside the walls.
"It's not hard to plan, with the state, Cole County and Jefferson City all working together," Bill Farr, the Jefferson City-Cole County Emergency Management director, explained. "We're here to make sure everybody's safe, if something happens."