Colorado vs Kansas

The I-70 run between Denver and Kansas City crosses a wide gap, especially since Colorado overhauled its law. Under a statute effective January 1, 2025 (HB24-1055), Colorado requires a child under 2 to ride rear-facing, keeps a child in a car seat or booster through age 8, requires children under 9 to ride in the back seat, and now requires everyone under 18 to be restrained. Kansas sets no rear-facing age, releases a child from a booster at age 8 (or 80 pounds or 4 feet 9 inches), and has no back-seat requirement. On rear-facing, the booster, and the back seat, Colorado reaches further.

Colorado's previous law was relatively light, requiring rear-facing only under 1 and 20 pounds. The 2025 update raised the rear-facing requirement to age 2 (unless the child is over 40 pounds), extended the booster requirement to age 9, and added a back-seat requirement through age 8. It also made the rule a primary violation, meaning an officer can stop a driver for it alone. That single law moved Colorado from the middle of the pack to one of the stricter states in the region.

Colorado requires rear-facing until age 2; Kansas sets no rear-facing age. Colorado keeps a child in a booster until age 9; Kansas releases at age 8. Colorado requires children under 9 to ride in the back seat; Kansas has no back-seat rule. So a Kansas family driving into Colorado picks up three obligations at once: rear-facing under 2, a booster through age 8, and the back seat for older children. Pediatricians recommend all of these as best practice in both states, but only Colorado makes them legal requirements.

Neither state fixes a single dollar figure in the same way in its restraint statute, though Colorado's violation is now a primary offense. The law that applies is the law of the state you are driving in. On an I-70 trip, follow Colorado's stricter standard the whole way: rear-facing until age 2, a booster until age 9, and any child under 9 in the back seat. Set up your seats to Colorado's rules before you leave, and you will be covered no matter which side of the border you are on.