There are no federal laws regarding seat belt usage in motor vehicles, however, “All States require, at a minimum, that all children 3 or younger, weighing less than 40 lbs., or less than 40 inches tall, be secured in child restraint systems while traveling in motor vehicles.” NHTSA Summary
Beyond that, every state has different laws for adult and child passengers. Arizona, for instance, requires all front seat passengers to buckle up, but back seat passengers over 15 years of age are not required to do so. Not true in Texas. Texas requires all front and rear passengers to wear a seatbelt and enforcement officers can stop and ticket you at any time for failure to do so.
So, if you are from Arizona and are traveling in Texas, can you get a ticket for not wearing a seat belt in the back of the RV? Absolutely! Seat belt laws are enforced by the state in which you are traveling and you must follow the laws of that state.
How are you to keep up with all these differences? Our suggestion (and it is a good one) is that every passenger wear a seat belt in a moving vehicle. This protects you and your fellow passengers. In the event of a sudden stoppage or change in direction, all unsecured passengers (and pets) become projectiles inside the vehicle. Unbelted passengers can cause great harm to other passengers, especially the driver who may not be able to regain control of the vehicle when hit by an unrestrained passenger. Seatbelts save the lives of well over 10,000 people annually. It is the safe thing to do.
In a truck or SUV towing a trailer or fifth wheel, safe travel is pretty straight forward: it is really no different than every day driving. Everyone buckle up!
Motorhomes, however, can be a little more complicated, especially when traveling with children. The driver and front passenger have safety belts installed as any vehicle. Rear passengers should have access to seatbelts, but they may not be front-facing and they may only be lap belts. This can be a problem when it comes to children riding safely in your RV because all infant and booster seats should be placed in a forward facing seat. In order to safely and legally carry children in your RV, they need to be in a child or booster seat attached to a forward-facing vehicle seat with a three point belt system (lap and shoulder strap). Some RVs cannot accommodate this because there are no forward facing passenger positions other than the driver and front passenger. This should be a consideration when purchasing your RV.
How then can I safely travel in my motorhome with children? Choose a motorhome that has enough forward facing passenger seating to accommodate each child. This can be tricky. If an acceptable motorhome can’t be found, considering driving the children separately in another vehicle, properly secured, of course. This also provides a smaller vehicle for errands and sightseeing once your RV is set up in your campsite. If these will not work for you, look at towables (travel trailers and fifth wheels) and get a truck that can safely accommodate all passengers.
These choices are not always easy, but convenience and safety do not always go hand in hand.
For more study on passenger restraint laws, see the following:
Summary of Vehicle Occupant Protection and Motorcycle Laws (detailed by State)
Governors Highway Safety Association State Seat Belt Laws
Governors Highway Safety Association Child Passenger Safety Laws
How do you properly wear a seatbelt?
How are your neighbors doing?
Seat Belt Compliance by State (pdf)