Wyo. Stat. § 31-5-206: Overtaking on the right.

(a) The driver of a vehicle may overtake and pass upon the right of another vehicle only under the following conditions:

(i) When the vehicle overtaken is making or about to make a left turn;

(ii) Upon a roadway with unobstructed pavement of sufficient width for two (2) or more lines of vehicles moving lawfully in the direction being traveled by the overtaking vehicle.

(b) The driver of a vehicle may overtake and pass another vehicle upon the right only under conditions permitting the movement in safety. The movement shall not be made by driving off the roadway.