Colorado is one of a majority of states that has restrictions on passengers in the cargo bed of a pickup truck. For the most part, these laws are intended to protect younger passengers.
Colorado law. Colorado’s law states that: A person is prohibited from riding on the outside, top, hood or fenders or any other portion of a vehicle except that they may ride, while in a sitting position, in the cargo area of a vehicle if the area is fully or partially enclosed on all four (4) sides. ( §42-4-201(6)) A driver shall not knowingly permit a person to ride on the top, hood, fenders, or any other portion of a vehicle except that a passenger may ride, while in a sitting position, in the cargo area of a vehicle if the area is fully or partially enclosed on all four (4) sides. ( §42-4-201(6). The penalty is a fine of $35. No points are assessed.
Regardless of state law, you may wish to consult your policy to be certain that passengers in the bed or cargo space are covered. Because pickup truck beds are designed to carry cargo, not people, there are no federal requirements regarding passengers in cargo beds. Colorado also has separate laws regarding child restraints.
Colorado does not have a law specifically requiring animals to be secured when being transported in the open area of a vehicle. In other words, the animal does not need to be restrained or secured whether inside an enclosed part of the vehicle or within the cargo bed. However laws prohibiting animal cruelty may always be invoked if a police officer determines that a transportation method rises to the standard of cruelty to animals. Both the ASPCA and the American Humane Association recommend restraining dogs when transporting them in pickup truck cargo beds.