What age are children required to be in a car seat in a car seat or booster seat?

Children are typically required to be in a car seat or booster seat until they are at least 8 years old or reach a certain height, often around 4 feet 9 inches, depending on state laws. Most guidelines recommend using a rear-facing car seat for infants and toddlers until they outgrow its weight or height limits. Once they surpass those limits, children should transition to a forward-facing car seat and then to a booster seat until they are properly fitting in an adult seat belt. It's important to check specific state regulations, as they can vary.