Wash. Rev. Code § 30A.49.060
A merger which is to result in a state bank shall, unless a later date is specified in the agreement, become effective after the filing with and upon the approval of the director of the executed agreement together with copies of the resolutions of the stockholders of each merging state or national bank approving it, certified by the bank's president or a vice president and a secretary. The charters of the merging banks, other than the resulting bank, shall thereupon automatically terminate.
The director shall thereupon issue to the resulting state bank a certificate of merger specifying the name of each merging state or national bank and the name of the resulting state bank. Such certificate shall be conclusive evidence of the merger and of the correctness of all proceedings therefor in all courts and places, and may be recorded in any office for the recording of deeds to evidence the new name in which the property of the merging state or national bank is held.
RCW 30A.49.060