Webster is a town in and the county seat of Day County, South Dakota, United States. The population was 1,886 at the 2010 census.
The town was platted in 1880, and was named in honor of J. B. Webster, a pioneer settler.
Webster is located at 45°20′01″N 97°31′10″W.
According to the United States Census Bureau, the city has a total area of 1.49 square miles (3.86 km2), all land.
Webster has been assigned the ZIP code 57274 and the FIPS place code 69780.
At the 2010 census, there were 1,886 people, 878 households and 481 families living in the city. The population density was 1,265.8 inhabitants per square mile (488.7/km2). There were 1,007 housing units at an average density of 675.8 per square mile (260.9/km2). The racial makeup of the city was 95.1% White, 0.2% African American, 2.3% Native American, 0.2% Asian, 0.3% from other races, and 1.9% from two or more races. Hispanic or Latino of any race were 0.7% of the population.
There were 878 households, of which 25.4% had children under the age of 18 living with them, 41.8% were married couples living together, 9.1% had a female householder with no husband present, 3.9% had a male householder with no wife present, and 45.2% were non-families. 41.0% of all households were made up of individuals, and 21% had someone living alone who was 65 years of age or older.