Final answer:
When a load extends 4 feet or more from the rear of a vehicle, a 12-inch square solid red or fluorescent orange flag must be attached for visibility and safety.
Step-by-step explanation:
When a load extends 4 feet past the rear of a vehicle, a 12 inches square solid red or fluorescent orange flag must be attached to the end of the load. This requirement is set to increase visibility and safety, alerting other drivers on the road to the presence of an extended load. Different states may have variations in these rules, but the general standard is to use a brightly colored flag to warn others. It is important to comply with these regulations to ensure road safety and to avoid penalties for not properly marking an extended load.