Westport is a town in western Brown County, South Dakota, United States. The population was 133 at the 2010 census.
The town has the name of a railroad employee.
Westport is located at 45°38′56″N 98°29′50″W (45.648875, -98.497262).
According to the United States Census Bureau, the town has a total area of 0.24 square miles (0.62 km2), all land.
Westport has been assigned the ZIP code 57481 and the FIPS place code 70540.
As of the census of 2010, there were 133 people, 48 households, and 34 families living in the town. The population density was 554.2 inhabitants per square mile (214.0/km2). There were 51 housing units at an average density of 212.5 per square mile (82.0/km2). The racial makeup of the town was 92.5% White, 4.5% Native American, and 3.0% from other races. Hispanic or Latino of any race were 3.0% of the population.
There were 48 households, of which 37.5% had children under the age of 18 living with them, 62.5% were married couples living together, 4.2% had a female householder with no husband present, 4.2% had a male householder with no wife present, and 29.2% were non-families. 25.0% of all households were made up of individuals, and 12.5% had someone living alone who was 65 years of age or older.