The U.S. state of Washington has six telephone area codes. The state initially used a single area code (206) until it was divided in 1957 with the creation of area code 509 to serve Eastern Washington. In 1995, 206 was split again to serve just the Puget Sound region after area code 360 was created for the remainder of Western Washington. In 1997, area code 425 was assigned to Seattle's Eastside and South Snohomish County suburbs and area code 253 for the Tacoma area, leaving 206 for just the city of Seattle, closely neighboring cities in King and Snohomish counties, and Bainbridge Island in Kitsap County.
| Code | Created | Regions and cities | Description |
|---|---|---|---|
| 206 | January 1, 1947 | Seattle, Shoreline, Lake Forest Park, Mercer Island, Bainbridge Island, Vashon Island | Original statewide area code until 1957, when area code 509 was created for Eastern Washington. Further splits in 1995 to create area code 360 for most of Western Washington, and 1997 to form area codes 253 and 425. |
| 509 | January 1, 1957[1] | Eastern Washington, including Spokane, the Tri-Cities, Yakima, Walla Walla, and Wenatchee | Created in a split from area code 206.[2] |
| 360 | January 15, 1995[3] | Western Washington excluding most of the Seattle metropolitan area; includes Olympia, Kitsap County, Bellingham, and Vancouver | Overlay plan. NPAs 206, 253, and 425 are slated for inclusion in overlay.[4] |
| 564 | August 28, 2017[4] | ||
| 253 | April 27, 1997[5] | Southern Puget Sound region, including Tacoma, most of Pierce County, Auburn, and Federal Way | |
| 425 | April 27, 1997[5] | Eastside and southern Snohomish County, including Everett, Snoqualmie Pass, and Renton[4] |
