Is one windshield wiper permitted?

If the vehicle was originally equipped from the manufacturer with one wiper it is permitted. All other vehicles must be equipped with a device for cleaning rain, snow, or other moisture from the windshield capable of cleaning the windshield over two separate arcs, one each on the left and right side of the windshield. Wipers must be maintained in good working order. (RCW 46.37. ... more