Washington County Government in the Portland Metro Area

Washington County is one of three counties — alongside Multnomah and Clackamas — that form the core of the Portland metropolitan region. This page covers the structure of Washington County government, how its departments and elected offices function, the services it delivers to residents, and how its authority intersects with and differs from the City of Portland and the Metro regional government. Understanding Washington County's role is essential for navigating land use, elections, public health, and infrastructure decisions in the western portion of the Portland metro area.

Definition and Scope

Washington County is a home rule county in Oregon, operating under authority granted by the Oregon Constitution and Oregon Revised Statutes (ORS Chapter 203). Its population surpassed 620,000 as of the 2020 U.S. Census (U.S. Census Bureau), making it the second most populous county in Oregon. The county seat is Hillsboro, where the primary administrative campus and county courthouse are located.

Washington County government delivers a defined set of services — many of which are mandated at the state level and administered locally. These include property assessment and taxation, elections administration, public health services, community development, corrections, roads, and the operation of the justice system through the Washington County District Attorney and Circuit Court (the latter being a state court, not a county entity). The county's land area covers approximately 727 square miles, spanning urban communities such as Beaverton, Hillsboro, Tigard, and Tualatin, as well as unincorporated rural areas in the Tualatin Valley and Coast Range foothills.

Scope, Coverage, and Limitations

Washington County government's jurisdiction extends across all incorporated cities and unincorporated territory within its boundaries. County authority does not replace the municipal authority of cities like Beaverton (population ~100,000 as of the 2020 Census) or Hillsboro — those cities maintain their own charters, councils, and land use programs. Washington County's development services and zoning regulations apply primarily in unincorporated areas; within city limits, municipal codes govern. State-level functions — Oregon Department of Transportation highways, Oregon courts, Oregon Health Authority programs — fall outside county authority even when physically located in Washington County. Readers seeking the broader regional governance structure, including Metro's role and Multnomah County's parallel functions, will find context at the Portland Government in Local Context page.

How It Works

Washington County operates under a Board of County Commissioners structure. The board consists of 5 elected commissioners representing districts across the county, with one commissioner serving as Board Chair. The Chair acts as the chief executive and is elected countywide, while the remaining 4 commissioners are elected by district. This hybrid structure — part legislative, part executive — is common among Oregon's larger counties.

The county's administrative operations are organized into departments overseen by appointed directors who report through a County Administrative Officer (CAO). Key departments include:

Assessment and Taxation — administers property valuation, tax billing, and collection for all taxing districts within the county
Elections — administers voter registration, ballot issuance, and election certification for all federal, state, and local elections held within the county
Land Use and Transportation — manages the county's comprehensive plan, zoning code for unincorporated areas, and the county road system (~1,400 centerline miles of county roads)
Public Health and Prevention — delivers communicable disease control, environmental health inspection, and community health programs under ORS Chapter 431
Community Corrections — supervises individuals on probation and post-prison supervision under contract with the Oregon Department of Corrections
Sheriff's Office — provides law enforcement in unincorporated areas, operates the county jail, and serves civil process countywide

The county budget is adopted annually by the Board of Commissioners following a process governed by Oregon Local Budget Law (ORS Chapter 294), which requires public notice, a citizen budget committee, and formal hearings before adoption.

Common Scenarios

Residents and businesses in the Portland metro west side encounter Washington County government in several recurring situations:

Property taxes: The Assessment and Taxation Department calculates assessed values and distributes tax obligations across overlapping taxing districts — school districts, fire districts, urban renewal areas, and Metro. A Washington County property tax bill may reflect levies from 10 or more separate taxing jurisdictions simultaneously. Relevant context on how property taxes work regionally appears at Portland Property Taxes.
Building permits in unincorporated areas: Residents outside city limits apply for building, land use, and septic permits through the county's Land Use and Transportation Department, not through any city bureau.
Voting and elections: All voters in Washington County register through the county Elections Division regardless of whether they reside in a city or unincorporated area. Washington County uses the statewide all-mail ballot system administered under ORS 254.470.
Public health services: County health programs serve all residents, including those in cities, for functions such as restaurant inspections, childhood immunizations, and communicable disease reporting — a function delegated from the Oregon Health Authority.
Urban growth boundary decisions: Washington County participates in urban growth boundary expansions coordinated through Metro. The boundary separates urban from rural land and directly affects development potential. See Portland Urban Growth Boundary for regional framing.

Decision Boundaries

Understanding when Washington County government is the relevant authority — versus a city, Metro, or a state agency — requires clarity on several boundary conditions.

Washington County vs. City Government: Inside Beaverton, Hillsboro, Tigard, or any incorporated city, land use decisions, building permits, and local ordinances fall under city jurisdiction. Washington County handles the same functions only in unincorporated territory. Property taxes, elections, and public health, however, remain county functions regardless of whether a resident lives inside or outside a city.

Washington County vs. Metro Regional Government: Metro holds authority over the urban growth boundary, regional land use planning policies, and facilities such as the Oregon Zoo and regional parks. Washington County implements land use decisions within its unincorporated territory consistent with Metro's regional framework but acts as its own land use authority. The Metro Regional Government page covers Metro's distinct role in detail.

Washington County vs. Multnomah County: The Willamette River and the West Hills generally mark the boundary between Washington and Multnomah counties. Portland's city limits extend into Washington County (notably the Sauvie Island area), but most Portland city services originate from Multnomah County infrastructure. Residents navigating cross-county questions can start at the Portland Metro Authority index for orientation across the full regional structure. For a parallel view of the county to the east, see Multnomah County Government and Clackamas County Government.

Washington County vs. State Agencies: Oregon Department of Transportation maintains state highways (including US 26 and OR 217) that run through the county. The Oregon judicial system — not the county — operates the Washington County Circuit Court, though the county funds the District Attorney's office and provides jail and court security. The Oregon Health Authority sets public health standards that county health departments implement.