Rosalia is a town in Whitman County, Washington, U.S.A. It is an agricultural community in the Palouse region, at an elevation of 2238 feet (682 m) above sea level. Its population was 550 at the 2010 census.
As of the census of 2010, there were 550 people, 228 households, and 151 families residing in the town. The population density was 887.1 inhabitants per square mile (342.5 /km2). There were 270 housing units at an average density of 435.5 per square mile (168.1 /km2). The racial makeup of the town was 96.5% White, 0.7% African American, 0.4% Native American, 0.2% Asian, 0.9% from other races, and 1.3% from two or more races. Hispanic or Latino of any race were 4.2% of the population.
There were 228 households of which 28.5% had children under the age of 18 living with them, 49.6% were married couples living together, 11.8% had a female householder with no husband present, 4.8% had a male householder with no wife present, and 33.8% were non-families. 27.6% of all households were made up of individuals and 14.1% had someone living alone who was 65 years of age or older. The average household size was 2.41 and the average family size was 2.89.
The median age in the town was 43.4 years. 24.4% of residents were under the age of 18; 6% were between the ages of 18 and 24; 21.1% were from 25 to 44; 31.9% were from 45 to 64; and 16.5% were 65 years of age or older. The gender makeup of the town was 50.5% male and 49.5% female.
