The crash occurred just before 1:30 p.m. in Gardner, the Grundy County coroner's and sheriff's offices said.
The girl's mother was driving north on Route 66 when she reached the stop sign at Route 53, police said.
Preliminary investigation indicates she lost control of the vehicle and rolled several times, coming to a final rest in the grassy field adjacent to the Gardner American Legion.
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The child was ejected from the vehicle and later transported to Morris Hospital.
Ryliegh Williams suffered multiple blunt force injuries and was pronounced dead upon arrival at the emergency room, the coroner's office said.
Records indicate the family was not from the area.
The crash remains under investigation.