Arkansas vs Missouri

Arkansas and Missouri agree on the early stages: neither sets a rear-facing age, and both require a young child to be in a car seat without naming the direction. The difference is how long the booster lasts. Missouri keeps a child in a car seat or booster until age 8, with a release at 80 pounds or 4 feet 9 inches. Arkansas ends the requirement at age 6 or 60 pounds, a full two years and 20 pounds earlier. Add a clear Missouri fine and a taxi exemption that only Arkansas grants, and Missouri is the stricter state, even though neither requires the back seat.

Missouri requires a child at least 4 but under 8 who weighs 40 to 79 pounds and is under 4 feet 9 inches to ride in a car seat or booster. The child is released only at 80 pounds, 4 feet 9 inches, or age 8. Arkansas releases a child at age 6 or 60 pounds, whichever comes first. So a 6-year-old who weighs 60 pounds is legally done in Arkansas but stays in a booster in Missouri until they hit 80 pounds, 4 feet 9 inches, or their 8th birthday. Missouri's higher thresholds keep a child protected closer to the point where a seat belt actually fits, though the American Academy of Pediatrics still recommends a booster past age 8 in both states.

Missouri states a clear penalty: an infraction with a fine of up to $50 plus court costs. Arkansas sets its fine in a separate section of the chapter, so the figure is less visible in the law itself. On exemptions, Arkansas is the looser of the two, excluding vehicles operated for hire such as taxis, while Missouri applies its rules to passenger vehicles with no general taxi or rideshare carve-out. Neither state requires children to ride in the back seat, though both recommend it for everyone under 13. Missouri does allow a lap belt only in a back seat position that has no shoulder belt, a narrow practical exception.

The law that applies is the law of the state you are driving in. Arkansas and Missouri meet along US 67, US 65, and I-49, with heavy family traffic heading north to the Branson area and south into Arkansas. To stay legal across the whole trip, follow Missouri's stricter rule: keep a child in a booster until age 8, or until they reach 80 pounds or 4 feet 9 inches, and use a child seat in a cab. A family moving from Arkansas to Missouri should plan for the booster to run about two years longer than they are used to.