[3] The area of the lower Willamette River has been inhabited for thousands of years, including by the Multnomah band of Chinookan peoples long before European contact, as evidenced by the nearby Cathlapotle village, just downstream.

Its creation was a result of a petition earlier that year by businessmen in Portland complaining of the inconvenient location of the Washington County seat in Hillsboro and of the share of Portland tax revenues leaving the city to support Washington County farmers.

(see:Portland Basin Chinookan Villages in the early 1800s, Boyd and Zenk,) Although Clark refers to the Willamette River as Multnomah, he may not have understood the meaning.

In 1924, the county's three commissioners were indicted and recalled by voters "in response to 'gross irregularities' in the award of contracts for construction of the Burnside and Ross Island bridges"; since all three had been supported by the Ku Klux Klan, their recall also helped reduce that organization's influence in the city.

[6] Vanport, built north of Portland in 1943 to house workers for Kaiser Shipyards, was destroyed by a flood five years later.

In 1968, the Oregon Legislative Assembly referred a bill, Ballot Measure 5, to voters that would amend the state constitution to allow for consolidated city-county governments when their populations are over 300,000.

[9][10][11] In the 2000 presidential election, Multnomah county played a decisive role in determining the winner of the state's electoral votes.

However, the library chose to turn down $104,000 per year of federal funding under CIPA to be able to continue to offer unfiltered Internet access.

[citation needed] On March 2, 2004, Multnomah County Chair Diane Linn announced the county would begin granting licenses for same-sex marriages, pursuant to a legal opinion issued by its attorney deeming such marriages lawful under Oregon law.

Her announcement was supported by three other commissioners (Serena Cruz, Lisa Naito, and Maria Rojo de Steffey), but criticized by Lonnie Roberts, who represents the eastern part of Multnomah County and was left out of the decision.

[19][failed verification] Within a few days, several groups joined to file a lawsuit to halt the county's action.

[20] The county government has also faced significant budget issues, including not being able to open the Wapato Corrections Facility since it was built in 2003.

The Oregon side of the Columbia River Gorge forms the eastern portion of the county's northern border.

The Multnomah County Central Courthouse opened in 2020, replacing a century-old building nearby that was in need of seismic retrofitting.

[52] Portland is one of the five largest auto import ports in the nation and is the West Coast's leading exporter of grain and lumber.

[53] The county is home to a number of Portland-area attractions and venues, including Oregon Museum of Science and Industry, Portland Art Museum, Memorial Coliseum, Oregon Convention Center, Moda Center, Providence Park, Washington Park, Oregon Zoo, International Rose Test Garden, Lan Su Chinese Garden, Portland Japanese Garden, Hoyt Arboretum and Pittock Mansion.

It is also home to the Historic Columbia River Highway, Multnomah Falls, and Oxbow Regional Park.

School districts include:[55] Portland Community College serves western portions of the county and Mt.