Unincorporated Urban Growth Areas (UGA) as defined by the Growth Management Act (GMA). The annual update is conducted by collecting UGA polygons directly from each of Washington's 39 counties. As of 2025, there are 27 counties with UGAs.All UGA polygons are normalized against the Department of Revenue's (DOR) "City Boundaries" layer (shared to the Washington Geoportal a.k.a. the GIS Open Data site: geo.wa.gov). The City Boundaries layer was processed into this UGA layer such that any overlapping area of UGA polygons (from authoritative individual counties) was erased. Since DOR polygons and county-sourced UGA polygons do not have perfect topology, many slivers resulted after the erase operation. These are attempted to be irradicated by these processing steps. "Multipart To Singlepart" Esri tool; exploded all polygons to be individualSlivers were mathematically identified using a 4 acre area threshold and a 0.3 "thinness ratio" threshold as described by Esri's "Polygon Sliver" tool. These slivers are merged into the neighboring features using Esri's "Eliminate" tool.Polygons that are less than 5,000 sq. ft. and not part of a DOR city (CITY_NM = Null) were also merged via the "Eliminate" tool. (many very small slivers were manually found yet mathematically did not meet the thinness ratio threshold)The final 8 polygons less than 25 sq. ft. were manually deleted (also slivers but were not lined up against another feature and missed by the "Eliminate" tool runs)Dissolved all features back to multipart using all fieldsAll UGAs polygons remaining are unincorporated areas beyond the city limits. Any polygon with CITY_NM populated originated from the DOR "City Boundaries" layer. The DOR's City Boundaries are updated quarterly by DOR. For the purposes of this UGA layer, the city boundaries was downloaded one time (4/24/2025) and will not be updated quarterly. Therefore, if precise city limits are required by any user of UGA boundaries, please refer to the city boundaries layer and conduct any geoprocessing needed. The DOR's "City Boundaries" layer is available here:https://www.arcgis.com/home/item.html?id=69fcb668dc8d49ea8010b6e33e42a13aData is updated in conjunction with the annual statewide parcel layer update. Latest update completed April 2025.