Castlewood is located in Hamlin county South dakota with a geographic area of 1.2 square miles. The total population in Castlewood is 582 with 48.8% male and 51.2% female. Children under age 5 represent 6.4% of the population, under age 18 equal 31.6% of the population and over age 65 is 17.4% of the population. The median household income is $60,893, per capita income is $27,615. There are a total of 231 housing units with 85.7% owner occupied. Education includes 33.3% of residents that are high school graduates and 24.2% with a bachelor's degree or higher. The average temperature in Castlewood in the summer is 68 degrees, and in the winter 15 degrees.