The accident happened at about 3 p.m. in the area of 300 West and 2300 South, according to Clearfield dispatchers. The girl fell to the pavement from the edge of the bed of the pickup, hitting her head.
The driver was also a 16-year-old girl and another girl was riding in the bed of the truck when the accident occurred.
The three had reportedly just come from Clearfield High School. The girl who fell was taken to the University of Utah Medical Center by helicopter. Police say she was unconscious when officers arrived, but regained consciousness inside the ambulance.
No citations have been issued, according to Clearfield Assistant Chief Mike Stenquist, The crash is still under investigation. Police say there was no indication that drugs or alcohol were involved.