The site of Tumwater has been home to Lushootseed-speaking peoples known as the Steh-Chass for thousands of years. Tumwater was originally called "New Market" by American settlers, and under the latter name was platted in 1845. The present name is derived from Chinook Jargon and means "waterfall". A post office called Tumwater was established in 1863. The city incorporated in 1875.
Geography
Tumwater is located at . Its northern neighbor is the state capital of Olympia. According to the United States Census Bureau, the city has a total area of, of which, is land and is water.
Based on per capita income, one of the more reliable measures of affluence, Tumwater ranks 89th of 522 areas in the state of Washington to be ranked. It is also the highest rank in Thurston County.
As of the census of 2010, there were 17,371 people, 7,566 households, and 4,460 families living in the city. The population density was. There were 8,064 housing units at an average density of. The racial makeup of the city was 85.0% White, 1.7% African American, 1.2% Native American, 4.8% Asian, 0.5% Pacific Islander, 1.6% from other races, and 5.2% from two or more races. Hispanic or Latino of any race were 6.2% of the population. There were 7,566 households of which 28.9% had children under the age of 18 living with them, 40.9% were married couplesliving together, 13.1% had a female householder with no husband present, 4.9% had a male householder with no wife present, and 41.1% were non-families. 31.6% of all households were made up of individuals and 9.7% had someone living alone who was 65 years of age or older. The average household size was 2.27 and the average family size was 2.83. The median age in the city was 35 years. 27% of residents were under the age of 18, 10% from 18 to 24; 31.7% were between the ages of 25 and 44; 26.8% from 45 to 64; and 13% were 65 years of age or older. The gender makeup of the city was 47.7% male and 52.3% female.
The Washington State Office of Financial Management indicates the 2019 population of the City of Tumwater was 24,040. As of the 2000 census, there were 12,698 people, 5,659 households, and 3,253 families living in the city. The population density was 1,276.1 people per square mile. There were 5,953 housing units at an average density of 598.2 per square mile. The racial makeup of the city was 88.41% White, 1.39% African American, 1.24% Native American, 3.90% Asian, 0.36% Pacific Islander, 1.50% from other races, and 3.21% from two or more races. Hispanic or Latino of any race were 4.08% of the population. There were 5,659 households out of which 28.3% had children under the age of 18 living with them, 41.5% were married couples living together, 12.3% had a female householder with no husband present, and 42.5% were non-families. 33.7% of all households were made up of individuals and 10.2% had someone living alone who was 65 years of age or older. The average household size was 2.20 and the average family size was 2.82. In the city, the age distribution of the population shows 23.2% under the age of 18, 10.9% from 18 to 24, 29.5% from 25 to 44, 23.0% from 45 to 64, and 13.5% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 89.8 males. For every 100 females age 18 and over, there were 84.5 males. The median income for a household in the city was $43,329, and the median income for a family was $54,156. Males had a median income of $41,778 versus $32,044 for females. The per capita income for the city was $25,080. About 4.3% of families and 8.5% of the population were below the poverty line, including 9.5% of those under age 18 and 5.2% of those age 65 or over.
