Authorities said the woman was driving a Toyota Camry "considerably" under the posted 60 mph speed limit when a 17-year-old girl from Wellsville driving a Ford Expedition approached from behind.
Not realizing how slowly the woman was moving, the teen hit the back of the Toyota, causing it to cross the median into oncoming traffic, where it clipped a Ford Crown Victoria driven by a 65-year-old Box Elder County man.
The Toyota then went into a ditch, stopping against a fence west of SR 89 near 2000 West, according to UHP.
All four occupants of the Toyota were taken to Logan-area hospitals; Urland was later flown by medical helicopter to Primary Children's Medical Center, where she died on Saturday, troopers announced on Sunday.
The girl's mother was flown to Intermountain Medical Center in Murray. An update on her condition was not immediately available on Sunday.
Authorities said all four were wearing seat belts or were in car seats at the time of the accident. The drivers in the other vehicles were not injured.
Troopers were investigating possible charges in the crash, said UHP Lt. Steve Winward.