Iowa vs Missouri

Iowa and Missouri each lead at a different stage, and Missouri comes out the stricter state overall. Iowa is tougher at the very start: it requires a child under 1 (and under 20 pounds) to ride rear-facing, a rule Missouri does not put in its statute. Missouri is tougher in the middle and later years: it keeps a child in a car seat or booster until age 8, with a release at 80 pounds or 4 feet 9 inches, while Iowa ends the required seat at age 6. Missouri's two extra booster years and a clearly stated fine outweigh Iowa's rear-facing rule on the overall tally, so Missouri is stricter, but the honest answer depends on your child's age.

Iowa requires a child under 1 who weighs less than 20 pounds to ride rear-facing. Missouri sets no rear-facing age at all; it requires only that a child under 4 or under 40 pounds be in a child restraint, with the direction left to the parent and seat manufacturer. So an Iowa parent can be cited for turning a young infant forward, while a Missouri parent cannot. Both rear-facing windows are short by best-practice standards, and pediatricians recommend rear-facing as long as the seat allows in both states, often past age 2.

Missouri keeps a child at least 4 but under 8 who weighs 40 to 79 pounds and is under 4 feet 9 inches in a car seat or booster, releasing them only at 80 pounds, 4 feet 9 inches, or age 8. Iowa allows the seat belt from age 6 with no height or weight condition. So a 6 or 7 year old of average size rides with the seat belt in Iowa but stays in a booster in Missouri. Missouri's higher thresholds keep a child 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. Iowa treats a violation as a simple misdemeanor set by the scheduled-fine statute rather than stating a dollar amount in the restraint section, and it does not convict a first rear-facing offense if the person later shows proof of acquiring a restraint. The law that applies is the law of the state you are driving in. Iowa and Missouri meet on I-35 between Des Moines and Kansas City and on I-29 along the western edge. To stay legal across the whole trip, combine each state's stricter rule: rear-face under 1 (Iowa), and keep a child in a booster until age 8 (Missouri).