At what speed must a driver move to the far right lane as close as possible to the right edge of the roadway?

The requirement for a driver to move to the far right lane as close as possible to the right edge of the roadway is typically associated with situations where the driver is traveling significantly below the maximum posted speed limit. Specifically, moving to the right lane is generally mandated when the driver is operating their vehicle at 10 mph or more below the maximum speed limit. This rule helps to ensure the smooth flow of traffic and allows faster-moving vehicles to pass safely, minimizing disruptions on the roadway.

While being in the right lane at any speed could be considered safe or appropriate in some contexts, the specific guideline emphasizes that behavior related to slower speeds should lead to positioning in the right lane. Thus, if a driver is going markedly slower than the surrounding traffic, which is 10 mph or more below the maximum speed limit, it is required for them to keep right to facilitate better traffic conditions. This helps prevent accidents and promotes efficient travel for all road users.

In contrast, the other situations mentioned do not align with standard driving practices regarding lane usage and speed. Being 5 mph under the speed limit or only moving to the right lane at a stop sign does not address the need for faster vehicles to pass or the principle of keeping slower vehicles to the right.