Vermont State Police say Jennifer Kinnarney, of South Royalton, was a passenger on the ATV driven by Anthony Potwin, 23, also of South Royalton.
Potwin rolled the ATV in a wooded area off of Ward Hill Road Tuesday afternoon, police said.
Kinnarney was taken by helicopter to Dartmouth Hitchcock Medical Center, where she died from her injuries.
Investigators say neither she nor Potwin were wearing helmets.
The cause of the crash is under investigation.
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