Final answer:
Slow-moving vehicles on interstate roads should remain in the rightmost lane for safety and traffic flow efficiency, only moving left to pass another vehicle.
Step-by-step explanation:
Slow-moving vehicles on interstate roads should stay to the right and use the rightmost lane, except when overtaking or passing another vehicle. Maintaining this position is critical for safety and helps to ensure the smooth flow of traffic. It is also in keeping with the regulations that govern road usage, where vehicles moving slower than the general flow of traffic should keep right to allow others to pass safely on their left.
When a slow-moving vehicle is preparing to pass another vehicle, it may enter the left lane to do so. However, it should return to the rightmost lane once the maneuver is complete. This helps manage traffic density and reduces the chances of high-speed vehicles encountering slower traffic in the left lanes, which could lead to dangerous situations and accidents.
It is similar to how a traffic signal operates to control the flow of vehicles. Such signals require vehicles to stop, preventing them from speeding through intersections. In a sense, the practice of keeping to the right on highways naturally signals faster traffic that they may overtake, thereby controlling the flow and speed similarly.