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.
Rosalia was founded in 1870 by T.J. Favorite, who named it for his wife. Rosalia was officially incorporated on March 23, 1894.
Historical population statistics from the U.S. Census Bureau