North American NumbersEastern Washington (Spokane)
Area code 509 serves all of eastern Washington east of the Cascade Mountains, anchored by Spokane and the Tri-Cities. It was the state's first split, in the 1950s, and remains a single unsplit code.
Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.
Where 509 is
Eastern Washington, roughly all counties east of the Cascade crest..
Communities served wholly or partly by 509:
Richland, Pasco, and Kennewick form the Tri-Cities. Less densely populated than western Washington.
How it relates to other codes
The codes 509 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?
How 509 got here
How full it is
Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.
Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.