Cristal Ramirez recently saw a picture from two years ago and though, “We look so much younger!”

It wasn’t any old throwback, but a shot from around when Ramirez and the band she fronts, Utah pop-rock quartet the Aces, last played Austin City Limits Music Festival.

Since then, the band — Ramirez on lead vocals and guitar, her sister Alisa on drums, Katie Henderson on guitar and McKenna Petty on bass — has released their debut full-length, “When My Heart Felt Volcanic.” It’s tight album of fizzy songs like “Stuck” and “Lovin’ Is Bible” and emotive tracks meant for just you, your AirPods and a big mood, like “Strong Enough” and “Waiting For You.”

But ACL Fest 2017 and a 2018 album are drops in the Aces’ bucket, relatively speaking. The group got started when its members were still in elementary school. Yes, elementary. About 13 years ago, by their estimate, the majority of their lives. You can tell just by how they talk about each other.

“It’s a huge part of all of our identities and I don’t know what we’d do without it,” Cristal Ramirez says. “It’s kind of a sisterhood. It’s something that’s so strongly a part of our lives and who we are as people. … When you’re in a band like that, you do so much more than write music or play music. You spend every day together. You’re touring together. You see each other in every scenario, every walk of life. It’s past friendship at this point.”

You’d imagine that kind of continuity forms a bond that the music industry can’t easily shake — having each other’s backs.

“Actually we stab each other in the back,” Alisa Ramirez says, followed by laughter from the rest of the band. “We have each other’s back super hard. I honestly think our relationship has continually been getting better over the years. We’ve known each other since we were little kids, all through our teens. Honestly, even now as we’re adults, and we’re settling into our independent lives and we all have our own houses and things like that, I just feel like it’s getting better and better.”

The ultimate rule of the Aces is making sure everyone is heard and listened to, Cristal says: “We operate from a place of love and compassion and care for each other.”

During their Friday set on the American Express stage in the early afternoon, a sizable crowd gathered to dance away the 48-degree blues. Many surrounding the headliner-sized stage sang along to the Aces’ songs, and not just the singles. Cristal strutted up and down the stage to the beat of her sister’s drums, the thrum of Petty's bass, the sparkle of Henderson's guitar, fully expressive. The strong gusts of cold-front wind helped make for some music video-ready hair, but Cristal didn’t need it. Charisma was at a 10 on songs like “Fake Nice” and “Volcanic Love.”

Imagine keeping a project going since you were in fifth grade. We ask if the band's success — a record deal, millions of streams, a stage upgrade at ACL Fest — feels like an arrival.

“Every once in awhile, someone goes viral overnight,” Cristal says. “But very rarely were they not slaving away at their craft for years.”

Listen to our full interview with the Aces for more, including how they use of pronouns in their lyrics. Get more ACL Fest coverage at austin360.com/acl.