Geddes is a city in central Charles Mix County, South Dakota, United States. The population was 208 at the 2010 census. Brady Allen Koopal is the mayor.
Geddes was laid out in 1900.
Geddes is located at 43°15′11″N 98°41′53″W.
According to the United States Census Bureau, the city has a total area of 0.61 square miles (1.58 km2), all land.
As of the census of 2010, there were 208 people, 110 households, and 57 families residing in the city. The population density was 341.0 inhabitants per square mile (131.7/km2). There were 155 housing units at an average density of 254.1 per square mile (98.1/km2). The racial makeup of the city was 96.2% White, 0.5% Native American, 0.5% Asian, 0.5% from other races, and 2.4% from two or more races. Hispanic or Latino of any race were 1.0% of the population.
There were 110 households of which 18.2% had children under the age of 18 living with them, 45.5% were married couples living together, 3.6% had a female householder with no husband present, 2.7% had a male householder with no wife present, and 48.2% were non-families. 45.5% of all households were made up of individuals and 22.7% had someone living alone who was 65 years of age or older.