The original people of the region were the Chemnapum Indians (closely related to the Wanapum tribe), living near the mouth of the Yakima River.

Lewis and Clark passed through the area in 1805, and an expedition of the Army Corps of Topographical Engineers headed by Robert E Johnson mapped the Yakima Valley in 1841.

[citation needed] An irrigation canal from the north side of Horn Rapids Dam was built in 1908 to bring water into Richland.

[citation needed] The Yellowstone Trail, a national highway stretching from Albany, New York, to Seattle, was located through the Yakima Valley in 1917 and 1918.

[citation needed] During the 1940s, the city of Richland was built, run and maintained by the War Department for the duration of the Manhattan Project.

A number of residents had chafed at the government's regulations, and as a result many of them had moved across the Yakima River, where it was possible to purchase land and own (rather than rent) a house.

[citation needed] Carl Heminger purchased some 80 acres (320,000 m2) in 1948, and laid out plans for a city.

[citation needed] West Richland was officially incorporated on June 17, 1955, combining the two towns of Heminger City and Enterprise.

[citation needed] In 2008, West Richland was the location of the speed test for the fastest production car in the world (the Aero SSC TT) at over 250 mph (400 km/h).

17.0% of all households were made up of individuals, and 4.5% had someone living alone who was 65 years of age or older.

17.2% of all households were made up of individuals, and 4.0% had someone living alone who was 65 years of age or older.