Wash. Rev. Code § 35.60.030
Municipalities are authorized to participate in any world fair or exposition to be held within the state by the state or any political subdivision or municipal corporation thereof, whether held within the boundaries of such municipality or within the boundaries of another municipality. Any municipality so participating is authorized, through its governing authorities, to purchase, lease, or otherwise acquire property, real or personal; to construct, improve, maintain and equip buildings or other structures; and expend moneys for investigations, planning, operations, and maintenance necessary for such participation.
The cost of any such acquisition, construction, improvement, maintenance, equipping, investigations, planning, operation, or maintenance necessary for such participation may be paid for by appropriation of moneys available therefor, gifts, or wholly or partly from the proceeds of bonds of the municipality, as the governing authority of the municipality may determine.
RCW 35.60.030