Heed this well, O drivers in Oklahoma:
Upon a roadway which is divided into four or more lanes, a vehicle proceeding at less than the maximum posted speed, except when reduced speed is necessary for safe operation, shall not impede the normal flow of traffic by driving in the left lane.
That much you know, or should have known. As of the first of November, the following also applies:
Upon a roadway which is divided into four or more lanes, a vehicle shall be driven in the right-hand lane except when overtaking and passing another vehicle proceeding in the same direction or when preparing for a left turn at an intersection or into a private road or driveway. Provided, however, this paragraph shall not prohibit driving in a lane other than the right-hand lane when traffic conditions or flow, or both, or road configuration, such as the potential of merging traffic, require the use of lanes other than the right-hand lane to maintain safe traffic conditions.
This has the potential to make my afternoon commute interesting, since it involves two exits from the left lane.