Idaho vs Utah

Idaho and Utah run similarly light child restraint laws, and the comparison turns on a single stage: how the booster ends. Utah keeps a child in a booster until age 8, unless they have already reached 57 inches (4 feet 9 inches). Idaho ends the requirement a year earlier, at age 7, with no height test at all. Neither state sets a rear-facing age, and neither requires the back seat. So the practical difference is narrow but real: a 7-year-old is legally done in Idaho but still needs a booster in Utah, which makes Utah the stricter of the two.

Utah requires a child younger than 8 to be in a child restraint or booster unless they are 57 inches or taller, so a tall child can graduate early but an average child stays in to age 8. Idaho requires a child 6 years of age or younger to be in a safety restraint and allows the seat belt from age 7, with no height or weight condition. The result is that Idaho releases most children a year sooner, and it has no 4 feet 9 inch backstop to keep a small child boostered. The American Academy of Pediatrics recommends a booster until the seat belt actually fits, usually near 4 feet 9 inches and between ages 8 and 12, which is beyond either state's minimum.

Neither state sets a rear-facing age, so the direction an infant faces is left to the parent and seat manufacturer in both, though pediatricians recommend rear-facing as long as the seat allows. Neither requires a general back-seat placement, though Idaho directs that an otherwise unrestrained covered child be placed in the rear seat if all belts are in use. On rideshare, Utah is the more explicit: it states that the adult supervising a child in a taxi or transportation network company vehicle must provide the child restraint, so the rule follows the child into the ride.

The law that applies is the law of the state you are physically driving in. Idaho and Utah meet on I-15 between Pocatello, Idaho Falls, and the Utah line, and on I-84, busy routes for commuters and for families heading to the national parks. To stay legal across the whole trip, follow Utah's slightly stricter rule: keep a child in a booster until age 8 or 4 feet 9 inches, and bring a seat even for a rideshare. A family moving from Idaho to Utah only needs to add about a year to the booster stage and to note Utah's rideshare instruction.