Richland, Pasco and Kennewick are collectively referred to as the Tri-Cities, Washington.
According to the United States Census Bureau, the city has a total area of 97.8 km² (37.8 mi²). 90.2 km² (34.8 mi²) of it is land and 7.6 km² (2.9 mi²) of it is water. The total area is 7.79% water.
As of the census of 2000, there are 38,708 people, 15,549 households, and 10,682 families residing in the city. The population density is 429.2/km² (1,111.8/mi²). There are 16,458 housing units at an average density of 182.5/km² (472.7/mi²). The racial makeup of the city is 89.55% White, 1.37% African American, 0.76% Native American, 4.06% Asian, 0.11% Pacific Islander, 1.85% from other races, and 2.31% from two or more races. 4.72% of the population are Hispanic or Latino of any race.
There are 15,549 households out of which 34.1% have children under the age of 18 living with them, 56.0% are married couples living together, 9.3% have a female householder with no husband present, and 31.3% are non-families. 27.2% of all households are made up of individuals and 9.4% have someone living alone who is 65 years of age or older. The average household size is 2.48 and the average family size is 3.02.
In the city the population is spread out with 27.2% under the age of 18, 7.5% from 18 to 24, 27.1% from 25 to 44, 25.4% from 45 to 64, and 12.8% who are 65 years of age or older. The median age is 38 years. For every 100 females there are 96.0 males. For every 100 females age 18 and over, there are 93.2 males.
The median income for a household in the city is $53,092, and the median income for a family is $61,482. Males have a median income of $52,648 versus $30,472 for females. The per capita income for the city is $25,494. 8.2% of the population and 5.7% of families are below the poverty line. Out of the total people living in poverty, 10.8% are under the age of 18 and 5.6% are 65 or older.