RCW 35A.57.020: Metropolitan municipal corporations—May be formed around charter code city.

Any area of the state containing two or more cities, at least one of which is a code city having at least ten thousand population, may organize as a metropolitan municipal corporation. The presence in such area of a code city having at least ten thousand population, shall fulfill the requirement of RCW 35.58.030 as to the class of city required to be included in an area incorporating as a metropolitan municipal corporation.