The minimum speed rule prevents a person from operating a motor vehicle in a manner that is too slow to allow for normal and reasonable movement of traffic.
According to the National Highway Safety Traffic Administration, the minimum speed rule is in place to ensure that motorists do not operate their vehicles in a way that causes problems with normal traffic flow. There is, however, also a basic speed rule, which states that motorists must travel at speeds that are reasonable and safe. When these two rules conflict, the basic speed rule takes a back seat. If traffic requires slower travel, then a motorist may travel below the normal minimum speed limit so as not to cause an accident.