Washington County Codes

In 1935, Washington began to issue license plates by county. A one- or two-letter prefix denoted the county, and letters were assigned by the order of population, with King County, the most populous, receiving letter A, followed by Pierce with B, and so on. After letter Z, the 13 smallest counties received two-letter prefixes derived from the county name.

1935 County Plates cropped
This photo from the Washington State Archives shows a complete county set from the first year of county coding, taken on the steps of the northeast corner of the state capitol

In 1954 the system remained the same, except the county code became a suffix. In 1958, the codes were adapted to conform with the ABC 123 numbering format. By 1980 the system became too complex to manage and the state discontinued the practice.

County Seat 1935-1957 1958-1981
King Seattle A AAA-AZZ, OAA-OZZ, IAA-IZZ, UCA-UZZ
Pierce Tacoma B BAA-BZE, TBA-TZZ, XYT
Spokane Spokane C CAA-CYE, SLA-SZZ
Snohomish Everett D DAA-DNM
Yakima Yakima E EAA-EJM
Whatcom Bellingham F FAA-FEJ, XYS
Clark Vancouver G GAA-GLZ, HHA-HHK
Grays Harbor Montesano H HAA-HDE
Kitsap Port Orchard I KSA-KYD, XYA
Thurston Olympia J JAA-JDK
Chelan Wenatchee K KAA-KCR
Lewis Chehalis L LAA-LCX
Skagit Mount Vernon M MAA-MDG
Cowlitz Kelso N NAA-NER
Walla Walla Walla Walla O WWA-WYN
Whitman Colfax P PAA-PCE
Clallam Port Angeles Q CLA-CMZ, PDA-PDZ
Benton Prosser R RAA-RET
Kittitas Ellensburg S SAA-SBH
Lincoln Davenport T TAA-TAN
Okanogan Okanogan U UAA-UBE
Pacific South Bend V VAA-VAU
Stevens Colville W WAA-WBC
Mason Shelton X XAA-XAW
Jefferson Port Townsend Y YAA-YAM
Klickitat Goldendale Z ZAA-ZAZ
Adams Ritzville AD YYA-ZAZ
Asotin Asotin AN ZYA-ZYG, ZZA-ZZZ
Columbia Dayton CO CUA-CUG
Douglas Waterville DO DSA-DSR
Franklin Pasco FN FNA-FRV
Ferry Republic FY FYA-FYE
Garfield Pomeroy GA GDA-GDF
Grant Ephrata GT GTA-GVL
Island Coupeville IS ISA-ITR (’58-’62 CYA-)
Dept. of Licensing JJ JJA-JJZ, XXA-XXZ, XYB-XYR
Dept. of Licensing (1939-1942) LD
Pend Oreille Newport PO PEB-PED, PEP, PER, PES
San Juan Friday Harbor SJ SJA-SJF
Skamania Stevenson SA SKA-SKJ
Wahkiakum Cathlamet WA WMA-WMF