Lewiston is a census-designated place (CDP) in Trinity County, California, United States.

[2] 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.

[3] According to the United States Census Bureau, the CDP has a total area of 51.8 square kilometers (20.0 sq mi), all land.

[4] It experiences hot summers and cool winters with great diurnal temperature variation.

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.

There were 696 housing units at an average density of 34.8 per square mile (13.4/km2), of which 404 (73.1%) were owner-occupied, and 149 (26.9%) were occupied by renters.

24.2% of all households were made up of individuals, and 11.6% had someone living alone who was 65 years of age or older.

In the California State Legislature, Lewiston is in the 2nd Senate District, represented by Democrat Mike McGuire,[24] and the 2nd Assembly District, represented by Democrat Chris Rogers.