Tenino is a city in Thurston County, Washington, United States. The population was 1,695 at the 2010 census. Tenino was officially incorporated on July 24, 1906, though it existed as a rural community since the mid-19th century. Initially, American settlers were attracted to the open prairies created and maintained by local natives through controlled burns to cultivate camas root, a staple food source. Records indicate the initial settlers' community centered on the prairie approximately 1/2 mile south of the present town. Early residents named their first post office and school "Coal Bank", in the 1860s, a reference to a nearby coal outcropping. When the Northern Pacific Railway arrived in 1872 they adopted Tenino as the name of the new station. It also appears informally as "T-9-O," a shortened variation in use as early as 1873.