Tualatin /tuːˈɔːlətᵻn/ is a city located primarily in Washington County in the State of Oregon. A small portion of the city is also located in neighboring Clackamas County. It is a southwestern suburb in the Portland Metropolitan Area that is located south of Tigard. The population was 26,054 at the 2010 census.

The name of the city is taken from the Tualatin River, which flows along most of the city's northern boundary. It is probably a Native American word meaning "lazy" or "sluggish" but possibly meaning "treeless plain" for the plain near the river or "forked" for its many tributaries. According to Oregon Geographic Names, a post office with the spelling "Tualitin" was established November 5, 1869, and the spelling changed to "Tualatin" in 1915.

In the 1850s, the settlement was first called Galbreath after its founder Samuel Galbreath. In 1853, Galbreath built the first bridge over the Tualatin river, and the town became known as Bridgeport. In the 1880s, John Sweek platted a town around the new railroad depot, and named the town Tualatin. It was incorporated as the City of Tualatin in 1913.

In 1962, a fossilized mastodon was excavated in what is now the Fred Meyer parking lot. It is now on display in the lobby of Tualatin Public Library.

As of the census of 2010, there were 26,054 people, 10,000 households, and 6,762 families residing in the city. The population density was 3,169.6 inhabitants per square mile (1,223.8/km²). There were 10,528 housing units at an average density of 1,280.8 per square mile (494.5/km²). The racial makeup of the city was 80.4% White, 1.2% African American, 0.7% Native American, 3.5% Asian, 1.0% Pacific Islander, 8.9% from other races, and 4.2% from two or more races. Hispanic or Latino of any race were 17.3% of the population.

...
Wikipedia