Michigan vs Wisconsin

Michigan and Wisconsin land on the same booster rule, so this comparison turns on the early years and the back seat. Both keep a child in a booster until age 8 or 4 feet 9 inches (Wisconsin adds an 80-pound trigger). Michigan pulls ahead in two places. It requires rear-facing until age 2, a full year past Wisconsin's age 1, and it follows that with a forward-facing harness until age 5. Michigan also requires a child under 4 to ride in the back seat, which Wisconsin does not. Those rules at the younger ages make Michigan the stricter state, even though the two converge once a child reaches the booster.

Michigan requires a child to ride rear-facing until age 2, then forward-facing with a harness until age 5. Wisconsin requires rear-facing only under age 1, then a forward-facing harness for a child 1 to under 4 who weighs 20 to under 40 pounds. So Michigan keeps a child rear-facing a year longer and runs the harness stage to a higher age. A Michigan parent can be cited for turning an 18-month-old forward, while a Wisconsin parent cannot. Both states recommend rear-facing as long as the seat allows, but Michigan's statutory floor is higher.

Michigan requires a child under 4 to ride in the back seat if the vehicle has one. Wisconsin has no back-seat requirement. At the booster stage the two states match: a child stays in a booster until age 8 or 4 feet 9 inches, with Wisconsin also releasing a child at 80 pounds. So for a 5, 6, or 7 year old, the two laws are effectively the same, and the difference is concentrated in the rear-facing, harness, and back-seat rules for younger children. The American Academy of Pediatrics recommends a booster until the belt fits in both states.

The law that applies is the law of the state you are physically driving in. Michigan and Wisconsin meet in the Upper Peninsula along US 2 and US 141, with Menominee, Michigan and Marinette, Wisconsin sitting across the river from each other. To stay legal across the whole trip, follow Michigan's stricter rules: rear-face until age 2, keep a harnessed seat until age 5, and seat a child under 4 in the back. A family moving from Wisconsin to Michigan picks up a longer rear-facing stage and a back-seat requirement, while the booster stage stays the same.