Long before there was Spotify or YouTube, Johnny Cash sat down and made a list of the 100 most essential country music songs. The list was intended not for fans, nor as part of his own storied career in country music, but rather as a gift for his daughter, Rosanne Cash. In Cash's eyes, this list would help her navigate the music that was her birthright.

Perhaps it is because this list of music was always so personal to the Cash family that Rosanne has never released it to the public in full. When she was 18 and on the road with him, the younger Cash tells NPR's Fresh Air, her famous father realized that his daughter's knowledge of the music he considered essential had some gaps.

"We were riding on the tour bus one day, kind of rolling through the South, and he mentioned a song. We started talking about songs, and he mentioned one, and I said I didn't know that one. And he mentioned another. I said, 'I don't know that one either, Dad,' and he became very alarmed that I didn't know what he considered my own musical genealogy," Cash recalls. "So he spent the rest of the afternoon making a list for me, and at the end of the day, he said, 'This is your education.' And across the top of the page, he wrote '100 Essential Country Songs.'"

Now an accomplished musical artist in her own right, Cash honored that collection of songs on her 2009 studio album, appropriately titled The List, which consists of a selection of 12 of the tracks her father named when he created that titular list. The track list features classics such as "Motherless Children," the southern gospel traditional popularized by the Carter Family, and "Take These Chains From My Heart," the last song Hank Williams ever recorded.

When her album first came out, Cash clarified to The Boot that she didn't make the project specifically to honor her father. "This record is not favorite songs of my dad, it's not a tribute," she said. "It's more a legacy of music that informs not just him and me, but all Americans. I mean, this music is as much who we are as Americans as the Civil War or anything else."

Despite its universal significance, the list is still a personal family treasure, and Cash doesn't plan to reveal it in full to the public. According to Zee News, Cash has indicated that the folk favorite "This Land Is Your Land" appears on the list, but noted that she had chosen not to record such a well-known standard for The List. Outside of her 2009 album, the singer has cut two more of her dad's selections -- Porter Wagoner's "A Satisfied Mind" (with Neko Case) and Mickey Newbury's "Sweet Memories" -- but she's still keeping the bulk of the list private.

"I like having it as my own," she explains, according to Zee News. "It's like a martial arts secret."

Meanwhile, Here's The Boot's List of Essential Country Songs