Sweeney collided with the wall and delayed the competition, but walked away on her own power.
She was taken to hospital for assessment.
"The final run of women's singles luge is now ongoing, but it has been marred by a very scary moment, as USA's Emily Sweeney suffered a nasty crash and did not finish".
The 24-year-old then fell off her sled and slammed into the barriers by herself.
"I'm very sore, and pretty stiff", she said to NBC's Lewis Johnson. I'm going to get an X-ray on my back after this, but I wanted to have the last word.
It's silent at the sliding center, she's out of the track and being looked at.
"I know I have a lot of support and I'm sorry that's how it ended".
Pyeongchang is Sweeney's first Olympics after missing the Sochi Games in 2014. Her dad was also spotted with a celebratory beer after his daughter's triumph, which is, as the saying goes, the ultimate "dad move".
The crash came on the treacherous stretch of the course from Turn 12 to Turn 9, where multiple athletes have faltered on this course.
"I've never been so relieved than when I saw her getting up and walking", said Summer Britcher, an American teammate of Sweeney's.
It took several minutes for Sweeney to get to her feet, then several more before she could finally start a slow walk to the finish area - surrounded by team and on-site medical personnel.
"Oh no, that's awful, you really hate to see that, where the athlete's feet go higher than her head".