Bridgewater is a city in southwestern McCook County, South Dakota, United States. The population was 492 at the 2010 census.
Originally named Nation, the present name recalls an episode when water had to be carried to the town site for the railroad. A post office called Nation was established in 1880, and the name was changed that same year to Bridgewater.
Bridgewater is located at 43°33′1″N 97°30′1″W (43.550192, -97.500319).
According to the United States Census Bureau, the city has a total area of 1.13 square miles (2.93 km2), all land.
Bridgewater has been assigned the ZIP code 57319, and the FIPS place code 07180.
As of the census of 2010, there were 492 people, 204 households, and 133 families residing in the city. The population density was 435.4 inhabitants per square mile (168.1/km2). There were 254 housing units at an average density of 224.8 per square mile (86.8/km2). The racial makeup of the city was 98.4% White, 0.4% Native American, 0.6% Asian, 0.4% from other races, and 0.2% from two or more races. Hispanic or Latino of any race were 2.0% of the population.
There were 204 households, of which 28.9% had children under the age of 18 living with them, 48.5% were married couples living together, 11.8% had a female householder with no husband present, 4.9% had a male householder with no wife present, and 34.8% were non-families.