Wash. Rev. Code § 70.77.517
It is unlawful for any person, except in the course of continuous interstate transportation through any state, to transport fireworks from this state into any other state, or deliver them for transportation into any other state, or attempt so to do, knowing that such fireworks are to be delivered, possessed, stored, transshipped, distributed, sold, or otherwise dealt with in a manner or for a use prohibited by the laws of such other state specifically prohibiting or regulating the use of fireworks. A violation of this section is a gross misdemeanor.
This section does not apply to a common or contract carrier or to international or domestic water carriers engaged in interstate commerce or to the transportation of fireworks into a state for the use of United States agencies in the carrying out or the furtherance of their operations.
In the enforcement of this section, the definitions of fireworks contained in the laws of the respective states shall be applied.
As used in this section, the term "state" includes the several states, territories, and possessions of the United States, and the District of Columbia.
RCW 70.77.517
Severability-2002 c 370: See note following RCW 70.77.126.