Portland metropolitan area in the context of Yamhill County, Oregon

Johnson Creek is a 25-mile (40 km) tributary of the Willamette River in the Portland metropolitan area of the U.S. state of Oregon. Part of the drainage basin of the Columbia River, its catchment consists of 54 square miles (140 km) of mostly urban land occupied by about 180,000 people as of 2012. Passing through the cities of Gresham, Portland, and Milwaukie, the creek flows generally west from the foothills of the Cascade Range through sediments deposited by glacial floods on a substrate of basalt. Though polluted, it is free-flowing along its main stem and provides habitat for salmon and other migrating fish.

Prior to European settlement, the watershed was heavily forested and was used by Native Americans of the Chinook band for fishing and hunting. In the 19th century, non-Native American settlers cleared much of the land for farming, and the stream is named for one of these newcomers, William Johnson, who in 1846 built a water-powered sawmill along the creek. By the early 20th century, a rail line parallel to the stream encouraged further residential and commercial development. As urban density increased in the floodplain, seasonal floods grew more damaging. In the 1930s the Works Progress Administration of the federal government lined the lower 15 miles (24 km) of Johnson Creek with rock to control the floods. Despite this, the creek flooded 37 times between 1941 and 2006. Since the 1990s, regional planners have tried to reduce flooding by controlling stormwater runoff, creating stream meanders, reducing erosion, replacing impervious surfaces, and protecting riparian buffers.

Skamania County (/skəˈmeɪniə/ skə-MAY-nee-ə) is a county located in the U.S. state of Washington. As of the 2020 census, the population was 12,036. The county seat and largest incorporated city is Stevenson, although the Carson River Valley CDP is more populous. Skamania County is included in the Portland-Vancouver-Hillsboro, OR-WA Metropolitan Statistical Area.

The Tri-County Metropolitan Transportation District of Oregon, branded as TriMet, is a transit agency that serves most of the Oregon part of the Portland metropolitan area. Created in 1969 by the Oregon legislature, the district replaced five private bus companies that operated in the three counties: Multnomah, Washington, and Clackamas. TriMet began operating a light rail system, MAX, in 1986, which has since been expanded to five lines that now cover 59.7 miles (96.1 km). It also operates the WES Commuter Rail line since 2009. It also provides the operators and maintenance personnel for the city of Portland-owned Portland Streetcar system. In 2024, the system had a ridership of 66,876,200, or about 202,800 per weekday as of the third quarter of 2025.

In addition to rail lines, TriMet provides the region's bus system, as well as LIFT paratransit service. There are over 650 buses on 79 lines as of September 2025. In 2018, the entire system averaged 310,000 rides per weekday and operates buses and trains between the hours of approximately 5 a.m. and 2 a.m. TriMet's annual budget for FY 2018 is $525.8 million, with 30% of resources coming from a district-wide payroll tax and 10% from fares. The district is overseen by a seven-person board of directors appointed by the state's governor. As of 2022, the agency has around 3,428 employees.

Vancouver (/væn.ˈkuː.vər/ van-KOO-vər) is a city in Clark County, Washington, United States, located on the north bank of the Columbia River. It had a population of 190,915 at the 2020 census, making it the fourth-most populous city in Washington. Founded in 1825 and incorporated in 1857, the city was originally established around Fort Vancouver, a fur trading outpost, and is situated directly north of Portland, along the Washington–Oregon state line. Vancouver serves as the county seat of Clark County and is part of the Portland metropolitan area.

Beaverton is a city in the Tualatin Valley, located in Washington County in the U.S. state of Oregon, with a small portion bordering Portland. The city is among the main cities that make up the Portland metropolitan area. Its population was 97,494 at the 2020 census, making it the second most populous city in the county and the seventh-most populous city in Oregon. Beaverton is an economic center for Washington County along with neighboring Hillsboro.

Oregon City is a city in and the county seat of Clackamas County, Oregon, United States, located on the Willamette River near the southern limits of the Portland metropolitan area. As of the 2020 census, the city population was 37,572. Established in 1829 by the Hudson's Bay Company, in 1844, it became the first U.S. city west of the Rocky Mountains to be incorporated.