Symbolism, Imagery, Allegory
Here's one we can all relate to regardless of when we're living: Music always seems to make things better.
Out of the Dust is filled with chapters where people go to concerts, talent contests, and other musical events to escape their hard times, but perhaps the most memorable incident occurs when the entire town turns out at the Joyce City Hardware Store to hear Mad Dog and the Black Mesa Boys perform live from the Amarillo Hotel on the radio. Billie Jo describes the euphoria and city pride of the moment when she says:
They sent / the dust swirling / cheering and whooping, / patting each other on the back, / as if they'd been featured on WDAG themselves. (93.4)
Did you catch that little dust reference in there? Music in this moment enables the townsfolk to send "the dust swirling"—to take charge of it, to kick it around for once instead of it always kicking them around. Pretty cool, right?
More specifically though, music is a form of salvation for Billie Jo, who believes from the beginning of the story that "my place in the world is at the piano" (28.1). Music is a place for her to retreat into when life becomes too much for her, like when Daddy and Ma get the news that there won't be enough seeds to plant wheat in the fall (20.3).
It's also a part of her Ma's legacy, a skill she passed onto Billie Jo. Even when Billie Jo's hands are burned in the fire, she still has the ability to play beautifully, even though she's so smothered in discouragement and sadness that she refuses to see it. It's only when she can move past her bitterness and grief that she can fully return to this gift Ma has given her and let it live on in her life.