Upon all highways of sufficient width, except one-way streets, the driver of a vehicle shall drive such vehicle upon the right half of the roadway. In passing or meeting, drivers shall give each other, as nearly as possible, at least one-half of the main-traveled portion of the roadway. The driver of a vehicle shall not drive to the left of the centerline of a highway in overtaking and passing another vehicle proceeding in the same direction unless such left side is clearly visible and is free of oncoming traffic for a sufficient distance ahead to permit such overtaking and passing to be made in safety.
(1958 Code § 16.39)