The driver of a vehicle intending to turn at an intersection shall do as follows:

    (1)     Right Turns. Both the approach for the right turn and a right turn shall be made as close as practicable to the right-hand curb or edge of the roadway.

    (2)     Left Turns:

        a.     On two-way roadways. At any intersection where traffic is permitted to move in both directions on each roadway entering the intersection, an approach for a left turn shall be made in that portion of the right half of the roadway nearest the centerline thereof, and by passing to the right of such centerline where it enters the intersection and after entering the intersection the left turn shall be made so as to leave the intersection to the right of the centerline of the roadway being entered. Whenever practicable, the left turn shall be made in that portion of the intersection to the left of the center of the intersection.

        b.     On other than two-way roadways. At any intersection where traffic is restricted to one direction on one or more of the roadways, the driver of a vehicle intending to turn left at any such intersection shall approach the intersection in the extreme left-hand lane lawfully available to traffic moving in the direction of travel of such vehicle and after entering the intersection the left turn shall be made so as to leave the intersection, as nearly as practicable, in the left-hand lane lawfully available to traffic moving in such direction upon the roadway being entered.

(Code 1964, § 12.295)

     State law reference(s)--Similar provisions, RSMo. § 300.215.