RCW 58.17.280: Naming and numbering of short subdivisions, subdivisions, streets, lots and blocks.

Any city, town or county shall, by ordinance, regulate the procedure whereby short subdivisions, subdivisions, streets, lots and blocks are named and numbered. A lot numbering system and a house address system, however, shall be provided by the municipality for short subdivisions and subdivisions and must be clearly shown on the short plat or final plat at the time of approval.