Dolly Parton's song catalog includes thousands of songs, including at least one fans won't get to hear until 2045. The unreleased, unheard track lives in a locked box at Dollywood's DreamMore Resort, to be shared 30 years after the resort's Summer 2015 opening.

In her new book Songteller: My Life in Lyrics, Parton shares that someone on her team dreamed up the idea of the song vault as an intriguing marketing idea. They specifically asked that she write a song to put in the locked box — created out of chestnut wood by her uncle Bill — which now resides in a glass display case.

"It would be a song that will never be heard until 30 years from the time we opened the resort. They said, 'You’ll be long dead,'" Parton writes. "I said, 'Well, maybe not. I'll be 99. I’ve seen people live to be older than that.'"

Parton was told that she had to keep the song a secret, and that she could not share it until the box was opened. "So I wrote this song, and I can say what it is," the country legend says.

"That's like burying one of my kids, putting it on ice or something, and I won't be around to see it brought back to life," she notes. "It's just burning me up inside that I have to leave it in there."

What Parton can share is that the song is contained in the box on a CD; in fact, she put a CD player in the box with it, because, she writes, "there's no telling what music is going to be by then."

"Hopefully, it will play and the whole thing ain't rotted," Parton jokes.

"Anyway, it's kind of weird or strange that they would ask me to write this mystery song," she adds. "I don’t know if I want to live to be 100 or not. But you never know. I might, and if I do, I’m going to be at that opening."

Dollywood opened in East Tennessee in 1986, after Parton purchased a stake in an existing theme park, Silver Dollar City — formerly Goldrush, Goldrush Junction and Rebel Railroad — in Pigeon Forge, Tenn. The park was a dream of Parton's, who grew up in the area and used her fame to bring more jobs, and more visitors, to the mountain town.

Dollywood has expanded plenty since its opening: In addition to the DreamMore Resort, the park has added rides, theaters and a water park. A $300 million expansion in the early 2010s added more jobs and amenities, and the park's Wildwood Grove area opened in 2018.

"I would honestly say that with all the awards and all the other things that I've done in my life, Dollywood is one of the greatest dreams that I've ever had come true," Parton tells News 24. "I am so proud of that I can't even begin to tell you. Dollywood is real special to me."

See Dolly Parton Through the Years:

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