Area code 360

This configuration was unchanged even with western Washington's explosive growth in the second half of the 20th century and the proliferation of cell phones, fax machines, and pagers.

By the early 1990s, the ensuing resource pressure meant that the need for additional central office prefixes and telephone numbers could no longer be staved off.

The restoration of these exurbs forced the Washington Public Utilities Commission to switch most of Seattle's suburban ring into areas 253 and 425 in 1998, sooner than originally planned.

This made 360 one of the few NPAs in the North American Numbering Plan without a continuous land border;[a] others include 706 in Georgia, 423 in Tennessee and 386 in Florida.

[5] Area code 564 is intended to eventually overlay other western Washington NPAs (206, 253, and 425) when demand requires numbering relief action.