The 1999 Legislature enacted a proposal by Attorney General Joe Mazurek and Governor Marc Racicot to reinstate numerical limits for cars and light trucks. The new speed limits are as follows. Applies to interstates within the Billings, Great Falls and Missoula areas. Night speed limits are in effect at any other time. The new law also requires motorists to operate their vehicles in a careful and prudent manner and at a reduced rate of speed, taking into account the traffic, weather, visibility and road conditions.
Laws prohibiting careless or reckless driving also are in effect on Montana roads.
These laws allow motorists to be stopped even if they are not exceeding the posted speed limit, if the speed at which they are traveling is considered too fast for conditions or dangerous to others on the road. The careful and prudent provision of the new law requires drivers to adjust their speeds according to the amount and character of traffic, visibility, weather and road conditions. For example, traffic may be heavy or light and may include trucks, cars, motor homes, farm equipment, and motorcycles. In addition, changing weather conditions may affect driver visibility and road conditions. These conditions may include fog or snow and road surface conditions such as water or ice.