From Salish Sea Wiki
Four Counties Comprise the Puget Sound Regional Council, are the center of political and economic power and share some transportation planning.
- Snohomish County - includes the east shore of Port Susan Bay Ecosystem and the Stillaguamish River and Snohomish River at the transition from Whidbey Basin to Central Puget Sound and the northern extent of The Megapolis. The City of Everett is its seat.
- King County - The heart of The Megapolis including the Cedar River and the Green/Duwamish River. The City of Seattle is its seat.
- Kitsap County - Extensive shorelines in the middle of Puget Sound, with West Sound on the east and Hood Canal to the west. The City of Port Orchard is its seat, and the City of Bremerton its largest market.
- Pierce County - The southern extent of The Magapolis in the Central Puget Sound Basin, including the Puyallup River, half the Nisqually River and some northern shores of South Puget Sound. The City of Tacoma is its seat.
From North to South are eight more rural counties:
- Whatcom County - The Mainland Shoreline of the San Juan Sub-Basin including the Nooksack River. The City of Bellingham is its seat.
- San Juan County - Encompassing the San Juan Islands with the City of Friday Harbor as its seat.
- Skagit County - Lowlands are dominated by the Skagit River and Samish River floodplains. The City of Mount Vernon is its seat.
- Island County - Including the west shore of the Whidbey Sub-basin including Port Susan Bay Ecosystem, and North Puget Sound. The City of Coupeville is its seat.
- Clallam County - Encompassing the Strait of Juan de Fuca Sub-Basin. The City of Port Angeles is its seat.
- Jefferson County - Including the transition from the Strait of Juan de Fuca to Hood Canal and the Port Townsend Ecosystem and Quilcene River. The City of Port Townsend is its seat.
- Mason County - Including the Southern extent of Hood Canal and the Skokomish River System, and the western shores of South Puget Sound. The City of Shelton is its seat.
- Thurston County - with shoreline in southernmost South Puget Sound Sub-basin including half the Nisqually River and the Dechutes River. The City of Olympia is its seat and the capital of the state.