Washington County, Oregon

Washington County is a county in Oregon, United States, on the western edge of the Portland
metropolitan area. It had a population of 600,372 at the 2020 census, an estimated 611,708 by
2025, and covers 724 square miles (1,880 km2) of land centred near 45°34′N 123°05′W.

Hillsboro is the county seat and largest city; its postal code is 97123. The county holds 12
incorporated cities, 15 census-designated places and roughly 49 smaller unincorporated
communities, and it runs on Pacific Time. Its FIPS code is 41067.

Towns & Villages in Washington County

Washington County has 12 incorporated cities, led by Hillsboro and Beaverton, the state’s
second and fifth most populous cities. Portland and Lake Oswego both extend a small edge into
the county but are counted primarily in Multnomah and Clackamas counties, so they are not listed
below. City stands for an Oregon municipal corporation; CDP is a census-designated place with no
local government of its own.

Washington County’s 15 census-designated places hold no city government of their own but
account for a large share of the county’s population, especially the Beaverton-Hillsboro
corridor:

Beyond the 12 cities and 15 CDPs above, county records name roughly 49 smaller localities with
no current Census population count of their own — rural crossroads and historic
communities such as Bacona, Helvetia, Scholls, Verboort and Manning. King City and Durham share
ZIP 97224 with the southern half of Tigard, and Aloha’s 97006 ZIP overlaps the northern edge of
Beaverton.

ZIP Codes

• 97123 — Hillsboro (also 97006 and 97124 serve parts of the city)
• 97005 — Beaverton (also 97006, 97007 and 97008 serve other parts of the city)
• 97223 — Tigard, shared with Metzger and Bull Mountain
• 97224 — King City, Durham and south Tigard
• 97062 — Tualatin
• 97116 — Forest Grove, also serving Cherry Grove and Dilley
• 97140 — Sherwood
• 97113 — Cornelius
• 97133 — North Plains
• 97106 — Banks (also 97109 and 97125 serve outlying parts of the city)
• 97119 — Gaston
• 97006 — Aloha (also 97003, 97007 and 97078 serve other parts of the CDP)
• 97229 — Bethany and Cedar Mill
• 97225 — Cedar Hills

Oak Hills, Rockcreek, Bull Mountain, West Haven-Sylvan, Garden Home-Whitford, West Slope,
Raleigh Hills, Marlene Village and Metzger have no ZIP code confirmed to their own boundary; mail
there is delivered under a neighboring city’s code.

Geography

Washington County sits at the south end of the Tualatin Valley, ringed by the Tualatin
Mountains, also called the West Hills, to the north and east, the northern Oregon Coast Range to
the west, and the Chehalem Mountains along its southern edge. Of its 726 square miles, 724 are
land and 2.2 are water, about 0.3 percent — the county has no large natural lake. Henry
Hagg Lake, a reservoir southwest of Forest Grove, is the county’s largest body of water, and the
Tualatin River, which drains most of the valley floor, is its principal river.

Clatsop County lies to the northwest, Columbia County to the north, Multnomah County to the
east, Clackamas County to the southeast, Yamhill County to the south, and Tillamook County to the
west. Clatsop County, Columbia County, Multnomah County, Clackamas County, Yamhill County and Tillamook County all border Washington
County directly.

Demographics

Washington County had a population of 600,372 at the 2020 census, the second-highest total of
Oregon’s 36 counties, and the latest estimate puts the county near 611,708 residents. Hillsboro
and Beaverton are by far the two largest communities, together holding well over a third of the
county’s population. Median household income runs $107,772 (2024), well above Oregon’s statewide
figure of $80,160 (2023 ACS). Population density works out to roughly 829 people per square mile
of land, among the densest counties in the state outside Multnomah.

Economy & Local Life

Manufacturing employs the most workers in the county, about 56,438 people, followed by health
care and social assistance at 40,956 and retail trade at 37,328. That manufacturing weight comes
from the Silicon Forest, the semiconductor and electronics cluster centered on the
Beaverton-Hillsboro corridor since the 1970s. Intel employs roughly 22,000 people across its
Hillsboro campuses, its largest concentration of employees anywhere. Nike’s world headquarters
sits on an unincorporated Washington County campus surrounded by the city of Beaverton. Forest
Grove is home to Pacific University, and Hillsboro Airport, the county’s general-aviation field,
hosts the Oregon International Air Show each summer. Hillsboro’s Fourth of July Parade is the
second-largest Independence Day parade in Oregon.

History

The Atfalati, a band of the Tualatin Kalapuya, lived in the Tualatin Valley before white
settlement. The Oregon provisional government created Twality District on 5 July 1843, one of the
original four districts of the Oregon Country. The Oregon Territorial Legislature renamed it
Washington County, after George Washington, in 1849.

Hillsboro was incorporated on 19 October 1876 and named for David Hill, an early Oregon
politician who sold part of his land claim to the county in 1850. Forest Grove, settled in the
1840s and incorporated in 1872, was the first city organized in the county and is now home to
Pacific University, founded the same decade. Cornelius traces to an 1845 settlement originally
called Free Orchards, renamed in 1893 for Thomas R. Cornelius, who built the town around a
planned rail line.

Getting There

US Route 26 crosses the county’s north side through Hillsboro and Beaverton. Oregon Routes 6, 8,
10, 47, 99W, 210, 217 and 219 also run through the county; Interstate 5 and Interstate 205 touch
its southeastern corner near Tualatin and Lake Oswego.

• Portland — about 12 miles east
• Salem — about 45 miles south
• McMinnville — about 25 miles southwest
• Vancouver, Washington — about 20 miles northeast

Portland International Airport, about 20 miles east of Hillsboro, is the nearest major
commercial airport. Hillsboro Airport, a general-aviation field on the city’s west side, is one
of the busiest airports in Oregon by traffic count but has no scheduled passenger service.
TriMet’s MAX Blue and Red light-rail lines connect Hillsboro, Beaverton and Portland; the nearest
Amtrak station is Portland Union Station.

Frequently Asked Questions

Where is Washington County located?
It sits on the western edge of the Portland metropolitan area, in the Tualatin Valley, bordered
by Clatsop, Columbia, Multnomah, Clackamas, Yamhill and Tillamook counties.

What is the population of Washington County?
600,372 at the 2020 census, with a 2025 estimate near 611,708 — the second most populous
county in Oregon.

How big is Washington County?
726 square miles (1,880 km2) total, of which 724 square miles are land.

What is the county seat of Washington County?
Hillsboro, incorporated in 1876, is the county seat and largest city.

How many towns and cities are in Washington County?
Twelve incorporated cities — Hillsboro, Beaverton, Tigard, Tualatin, Forest Grove,
Sherwood, Cornelius, King City, North Plains, Durham, Banks and Gaston — plus 15
census-designated places led by Aloha, Bethany and Cedar Mill.

What ZIP codes does Washington County use?
97123 and 97124 for Hillsboro; 97005 through 97008 for Beaverton; 97223 and 97224 for Tigard,
King City and Durham; 97062 for Tualatin; and 97116 for Forest Grove, among others.

What is Washington County known for?
The Silicon Forest tech corridor — Intel’s largest employment base and Nike’s world
headquarters both sit inside the county.

More counties in this state: Towns and villages in Oregon.