Maryland vs Pennsylvania

Maryland and Pennsylvania start from the same place for babies. Both require a child under 2 to ride rear-facing until they outgrow the seat's limits. The gap opens at the other end of childhood. Maryland lets a child leave the booster at age 8 OR once they reach 4 feet 9 inches, whichever comes first. Pennsylvania uses age 8 alone, with no 4 foot 9 inch shortcut in the statute. That single word, whichever, makes Pennsylvania the stricter state for a tall child: a 6-year-old who has already hit 4 feet 9 inches can ride with the seat belt in Maryland but must stay in a booster in Pennsylvania until their 8th birthday. For a child of average height the two laws land in the same spot around age 8.

On the early stages the states are close. Maryland and Pennsylvania both require rear-facing until age 2, and both require a child under 4 to be in a car seat. Maryland adds one softening detail: a first violation of the rear-facing requirement is a written warning rather than a fine, which gives new parents a single mistake before any money is owed. Pennsylvania does not carve out that grace for rear-facing specifically. Neither state requires children to ride in the back seat, though both recommend it for everyone under 13, and the American Academy of Pediatrics treats the back seat as the safest place for any child that age regardless of which state line you are on.

Pennsylvania carries the higher penalty. A car seat or booster violation is a summary offense with a flat $75 fine, and the money goes into the state's Child Passenger Restraint Fund. Maryland sets a $50 fine, and as noted a first rear-facing violation is only a warning. So Pennsylvania is both stricter on when the booster comes out and tougher on the wallet. Neither state offers a general taxi or rideshare exemption, so a child seat or booster is expected in a cab or rideshare in both Baltimore and Pittsburgh.

The law of the state you are physically driving in controls, not the state where you live. On the common Baltimore to Harrisburg or Philadelphia run up I-83 or I-95, the simplest way to stay legal the whole way is to follow Pennsylvania's stricter booster rule: keep any child under 8 in a booster even if they have already passed 4 feet 9 inches. Do that and you satisfy Pennsylvania while staying comfortably inside Maryland's rule. Families relocating from Maryland to Pennsylvania most often get tripped up by a tall older child, because Maryland would have let that child out of the booster at 4 feet 9 inches and Pennsylvania will not until age 8.