Lewiston, California  Lewiston is a census-designated place (CDP) in Trinity County, California, United States. The population was 1,193 at the 2010 census, down from 1,305 at the 2000 census. Lewiston is located at (40.699213, -122.810684). According to the United States Census Bureau, the CDP has a total area of , all land. This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F. According to the Köppen Climate Classification system, Lewiston has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps. A post office called Lewiston has been in operation since 1854. The community was named after Benjamin Franklin Lewis, adopted son of town founder, Tom Palmer, who, with Lewis, ran a gold mining operation on the Trinity River in the early days of the Gold Rush. Lewiston's Online Pioneer Museum: www.oldlewistonschoolhouse.org  The 2010 United States Census reported that Lewiston had a population of 1,193. The population density was 59.6 people per square mile (23.0/km²). The racial makeup of Lewiston was 1,074 (90.0%) White, 8 (0.7%) African American, 37 (3.1%) Native American, 6 (0.5%) Asian, 5 (0.4%) Pacific Islander, 21 (1.8%) from other races, and 42 (3.5%) from two or more races. Hispanic or Latino of any race were 78 persons (6.5%). The Census reported that 1,193 people (100% of the population) lived in households, 0 (0%) lived in non-institutionalized group quarters, and 0 (0%) were institutionalized. There were 553 households, out of which 112 (20.3%) had children under the age of 18 living in them, 267 (48.3%) were opposite-sex married couples living together, 45 (8.1%) had a female householder with no husband present, 20 (3.6%) had a male householder with no wife present. There were 44 (8.0%) unmarried opposite-sex partnerships, and 3 (0.5%) same-sex married couples or partnerships. 177 households (32.0%) were made up of individuals and 63 (11.4%) had someone living alone who was 65 years of age or older.