Published: July 25, 2016
The more populous, western part of Washington State is currently served by 4 area codes: 206, 253, 360 and 425. The Washington Utilities and Transportation Commission approved on May 19, 2016 the introduction of the new area code 564 which will initially overlay area code 360 and eventually the entire area currently served by the 4 aforementioned NPAs.
Plans for NPAs' 206, 253 and 425 relief will be announced at a later time.
See official NANPA announcement and map of the new overlay area (PDF document).
Visit area code 564 page for a list of cities served, map and other info.