Montana Title 61. Motor Vehicles § 61-8-328. Driving on roadways laned for traffic

(1) A vehicle must be operated as nearly as practicable entirely within a single lane and may not be moved from the lane until the operator has first ascertained that the movement can be made with safety.

(2) Upon a roadway that is divided into three lanes and that provides for two-way movement of traffic, a vehicle may not be operated in the center lane except:

(3) Official traffic control devices may be erected directing specified traffic to use a designated lane or designating those lanes to be used by traffic moving in a particular direction regardless of the center of the roadway. Operators of vehicles shall obey the directions of every official traffic control device that designates use of specific lanes.

(4) A person may turn a vehicle left across a lane marked with two yellow lines into a public or private parking lot, private road, private driveway, or roadway if the turn can be made safely and if the person does not hinder the flow of oncoming traffic.

(5) Official traffic control devices may be installed that prohibit the changing of lanes on sections of a roadway, and operators of vehicles shall obey the directions of those devices.

(6) A motor vehicle may not be driven or parked in a bicycle lane that is signed and delineated as a bicycle lane by official traffic control devices.