Governor Jennifer Granholm has signed legislation requiring all children who are both under age 8 and shorter than 4-foot-9 to be fastened into booster seats.
The new measure takes effect July 1st. Violators will face fines of up to $65 per offense.
It adds to Michigan law requiring children under 4 to ride in a child restraint system.
Sponsors of the legislation signed Thursday say most of the children between 4 and 8 years old who are seriously injured in auto accidents aren't restrained in a booster seat.
Michigan will become the 39th state to adopt an expanded booster seat law.