564 Area Code – Seattle, Washington: Location, Time Zone & History

Few area codes took as long to arrive as 564. Industry planners first proposed it in 1999 to relieve projected exhaustion of area code 360, but improved number-pooling efficiency kept pushing the launch back for years. It finally entered service on August 28, 2017, as an all-services overlay of 360 across western Washington, with mandatory ten-digit local dialing taking effect just a month earlier, on July 29, 2017, to prepare the region for it.

The rollout did not stop there. On June 15, 2023, the Washington Utilities and Transportation Commission approved expanding the overlay complex to also cover area code 206 in metropolitan Seattle, ahead of that code's own projected exhaustion, and the 206/564 overlay went live on June 10, 2025, letting carriers begin issuing 564 numbers within Seattle itself. This staged approach, layering the same new code onto two separate original area codes years apart rather than in one simultaneous overlay, is unusual among North American numbering plans.

The combined 360/206/564 territory stretches from Seattle to Vancouver, Everett, Bellingham, Olympia, and Bremerton, and spans industries including technology, aerospace, manufacturing, agriculture, timber, and tourism across the Puget Sound region.