Elizabeth Dazzio was driving her sister and a friend home from the singer's show in Louisiana when she fell asleep at the wheel.
Dazzio was knocked unconscious when the car crashed. The other two girls were trapped and unable to reach their phones.
"You could smell the gas and smoke," Dazzio's sister Caroline said. "I was just thinking we need to get out of this car."
The girls say other drivers on the highway kept speeding by, not noticing the crashed car. So to signal help, the girls lit up the flashing bracelets that had been handed out at Swift's concert.
Eventually a woman saw the blinking lights and called 911. All of the girls are expected to make a full recovery.
Taylor Swift, who saw the news story after the concert, tweeted a message saying she's glad to hear the girls are doing okay.