Lewiston is a semi-rural locality in South Australia, 6 km east of Two Wells and 12 km west of Gawler. At the 2011 census, Lewiston had a population of 2,947.
Lewiston is an animal and crop farming area.
Lewiston was named by local residents in December 1864, in honour of James William Lewis, Post Master General of South Australia from 1861 until 1869. Lewis had approved a branch Post Office for the Lewiston district, which was to operate from the school house.
The name Lewiston was first used when the branch Post Office opened on 1 February 1865. The first Post Mistress was Isabella Mitchell, wife of the school master William Mitchell.
The school opened in January 1857 and was known as the Port Gawler East school. In 1866 the name of the school was changed to Lewiston. The school closed in 1944 and was demolished.