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, Oregon, along the Washington–Oregon border. Vancouver serves as the county seat of Clark County and is part of the Portland metropolitan area.

Vancouver shares its name with the larger city of Vancouver in southern British Columbia, Canada, approximately 300 miles (480 km) to the north. Both cities were named after British sea captain George Vancouver, but the U.S. city is older. Vancouver, British Columbia, was incorporated 29 years after the incorporation of Vancouver, Washington, and more than 60 years after the name Vancouver was first used in reference to the historic Fort Vancouver trading post on the Columbia River. City officials have periodically suggested changing the U.S. city's name to Fort Vancouver to reduce confusion with its larger and better-known northern neighbor. Many Pacific Northwest residents distinguish between the two cities by referring to the Canadian city as "Vancouver, B.C." and the United States city as "Vancouver, Washington", or "Vancouver, USA". Local nicknames formerly included "Vantucky" (though this is used as a derogatory term) and "The 'Couv(e)".

The Vancouver area was inhabited by several Native American tribes, most recently the Chinook and Klickitat nations, with permanent settlements of timber longhouses. The Chinookan and Klickitat names for the area were reportedly Skit-so-to-ho and Ala-si-kas, respectively, meaning "land of the mud-turtles". First known European contact was made by William Robert Broughton in 1792, with approximately half of the indigenous population killed by smallpox before the Lewis and Clark Expedition arrived in the area in 1806. Within another fifty years, other diseases such as measles, malaria and influenza had reduced the Chinookan population from an estimated 80,000 "to a few dozen refugees, landless, slaveless and swindled out of a treaty".

Meriwether Lewis wrote that the Vancouver area was "the only desired situation for settlement west of the Rocky Mountains". The first permanent European settlement did not occur until 1824, when Fort Vancouver was established as a fur trading post of the Hudson's Bay Company. From that time on, the area was settled by both the US and Britain under a "joint occupation" agreement. Joint occupation led to the Oregon boundary dispute and ended on June 15, 1846, with the signing of the Oregon Treaty, which gave the United States full control of the area. Before 1845, American Henry Williamson laid out a large claim west of the Hudson's Bay Company (including part of the present-day Port of Vancouver), called Vancouver City and properly registered his claim at the U.S. courthouse in Oregon City, before leaving for California. In 1848, Williamson had it surveyed and platted by Peter Crawford. In 1850, Amos Short traced over the claim of Williamson and named the town Columbia City. It changed to Vancouver in 1855. The City of Vancouver was incorporated on January 23, 1857.

Based on an act of the 1859–60 legislature, Vancouver was briefly the capital of Washington Territory, before capital status was returned to Olympia by a 2–1 ruling of the territorial supreme court, in accordance with Isaac Stevens' preference and concern that proximity to the border with Oregon might give some of the state's influence away to Oregon.

The neighborhood of Sifton was the terminus of an early electric trolley operated by the Northcoast Power Company that also served nearby Orchards from 1910 until 1926. The trolleys made ten stops and ran once per hour, charging 15 cents each way. A mural in the heart of Orchards depicts the trolley and the rural character of the area at the time it was operating. The community was named after Doctor Sifton, a promoter of the trolley service.

According to the archives of the Vancouver Columbian newspaper, the Orchards-Sifton route ran along Vancouver's Main Street to 26th Street (renamed Fourth Plain Blvd.), then from 26th to K Street and thence north to 33rd Street. From there, it ran on 33rd over Burnt Bridge Creek and past the city limits. At that point the trolley became more like a regular train as it followed a cut through the wilderness. Few houses were seen between Vancouver and Orchards. The public's growing preference for motor cars in the 1920s heralded the end of the trolley.

Separated from Oregon until 1917, when the new Interstate Bridge began to replace ferries, Vancouver had three shipyards just downstream which produced ships for World War I before World War II brought an enormous economic boom. An Alcoa aluminum plant opened on September 2, 1940, using inexpensive power from the nearby New Deal hydropower turbines at Bonneville Dam. After the bombing of Pearl Harbor, Henry Kaiser opened a shipyard next to the U.S. Army base, which by 1944 employed as many as 36,000 people in a twenty-four hours a day, seven days a week production of Liberty ships, landing ship tanks, and escort carriers. This influx of shipyard workers boosted the population from 18,000 to over 80,000 in just a few months, leading to the creation of the Vancouver Housing Authority and six new residential developments: Fruit Valley, Fourth Plain Village, Bagley Downs, Ogden Meadows, Burton Homes and McLoughlin Heights. Each of these was later incorporated into the city, and are well-known neighborhoods, while the neighboring "shipyard city" of Vanport, Oregon, would be destroyed by the Memorial Day flood of 1948.^{[citation needed]}