Maryland Code, Transportation § 21-309

(a) On any roadway that is divided into two or more clearly marked lanes for vehicular traffic, the following rules, in addition to any others consistent with them, apply.

(b) A vehicle shall be driven as nearly as practicable entirely within a single lane and may not be moved from that lane or moved from a shoulder or bikeway into a lane until the driver has determined that it is safe to do so.

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

(d) The driver of a vehicle shall obey the directions of each traffic control device that directs specified traffic to use a designated lane or that designates those lanes to be used by traffic moving in a particular direction, regardless of the center of the roadway.

(e) The driver of a vehicle shall obey the directions of each traffic control device that prohibits changing lanes on sections of a roadway.

(f) On a roadway that has two or more lanes for traffic moving in the same direction, the driver of any truck, truck tractor, trailer, or bus shall obey the directions of each traffic control device that requires the vehicle to be driven in a certain lane.

(g) On a roadway along which a two-way left turn lane has been provided through traffic control devices, vehicles may not enter that lane except when preparing for or making a left turn from or into the roadway or when preparing for or making a U-turn, and may enter only if the lane is clear of an opposing movement.

(h) A vehicle shall be driven within a lane described under subsection (g) of this section the shortest distance practicable prior to making a left turn or U-turn or after making a left turn.

(i) On roadways along which a two-way left turn lane has been placed, left turns shall be made only from within such lane.