Immediately after the filing of the statement of an annexation election, the legislative body of the annexing city may, if it deems it wise or expedient, adopt an ordinance providing for the annexation. Upon the date fixed in the ordinance of annexation, the area annexed shall become a part of the annexing city. The clerk of the annexing city shall transmit a certified copy of this ordinance to the secretary of state and the office of financial management.
RCW 35.10.265