S
- Sagemoor
- Saginaw
- Sahalee
- Saint Andrews
- Saint Clair
- Saint Cloud
- Saint Helens
- Saint John
- Saint Urban
- Salkum
- Salmon Creek
- Samish
- Sammamish
- Sampson
- San de Fuca
- Sandy Bend
- Sappho
- Saratoga
- Satsop
- Satus
- Sauk
- Sawyer
- Saxby
- Scammon Landing
- Scandia
- Scenic
- Schlomer
- Schoonover
- Schrag
- Scotia
- Scott
- Seabeck
- Seahurst
- Seal Rock
- SeaTac
- Seattle
- Seattle Heights
- Sedro Woolley
- Sekiu
- Selah
- Selleck
- Seltice
- Semiahmoo
- Sequim
- Seven Bays
- Shadow
- Shaker Church
- Shano
- Shaw Island
- Shawnee
- Sheffler
- Shelter Bay
- Shelton
- Sheridan
- Sheridan Beach
- Sherman
- Shine
- Shore Acres
- Shoreline
- Shorewood
- Shreck
- Sieler
- Sightly
- Silcott
- Siler
- Silvana
- Silver Beach
- Silver Beach
- Silver Brook
- Silver Creek
- Silverdale
- Silverlake
- Silver Lake
- Silverton
- Similk Beach
- Sims Corner
- Sine
- Sisco
- Sixprong
- Skagit City
- Skamania
- Skamokawa
- Skokomish
- Skookumchuck
- Skykomish
- Skyway
- Slater
- Smith Place
- Smithville
- Smokey Point
- Smyrna
- Snake River
- Snee Oosh
- Snohomish
- Snoose Junction
- Snoqualmie
- Snoqualmie Pass
- Snoquera
- Snowden
- Soap Lake
- Sobey
- Sokulk
- South Bay
- South Beach
- South Bend
- South Broadway
- South Cle Elum
- South Hill
- South Montesano
- South Prairie
- South Snohomish
- South Wenatchee
- Spanaway
- Spangle
- Spee-Bi-Dah
- Spirit
- Spokane
- Sprague
- Spring Beach
- Springdale
- Spring Glen
- Spring Valley
- Stabler
- Staley
- Stampede
- Stanwood
- Starbuck
- Star Lake
- Startup
- State Camp
- State Line Village
- Stayman
- Stehekin
- Steilacoom
- Stentz Spring
- Steptoe
- Sterling
- Stevenson
- Stimson Crossing
- Strandell
- Stratford
- Striebels Corner
- Stringtown
- Stringtown
- Stuart
- Sudden Valley
- Sulphur
- Sultan
- Sumas
- Summit
- Summit
- Summitview
- Sumner
- Sundale
- Sunlight Beach
- Sunnybank
- Sunnydale
- Sunny Hill
- Sunny Shores
- Sunnyside
- Sunnyslope
- Sunnyslope
- Sunrise
- Sunrise Beach
- Sunset
- Sunset Beach
- Sunset Farm
- Sunshine
- Sunshine Beach
- Supplee
- Suquamish
- Susie
- Sutico
- Sutton
- Swale
- Swantown
- Swede Hill
- Swinomish Village
- Synarep