Porcupine, South Dakota
According to the United States Census Bureau, the CDP has a total area of 9.5 square miles (24.6 km²), all of it land.
Porcupine has been assigned the ZIP code 57772.
Porcupine is the unofficial capital of the self-proclaimed Republic of Lakotah.
As of the census of 2000, there were 407 people, 89 households, and 76 families residing in the CDP. The population density was 42.9 people per square mile (16.6/km²). There were 103 housing units at an average density of 10.8/sq mi (4.2/km²). The racial makeup of the CDP was 1.23% White, 98.28% Native American, and 0.49% from two or more races. Hispanic or Latino of any race were 1.47% of the population.
There were 89 households out of which 47.2% had children under the age of 18 living with them, 32.6% were married couples living together, 38.2% had a female householder with no husband present, and 13.5% were non-families. 9.0% of all households were made up of individuals and 1.1% had someone living alone who was 65 years of age or older. The average household size was 4.57 and the average family size was 4.83.
In the CDP the population was spread out with 42.0% under the age of 18, 13.5% from 18 to 24, 21.6% from 25 to 44, 18.9% from 45 to 64, and 3.9% who were 65 years of age or older. The median age was 21 years. For every 100 females there were 110.9 males. For every 100 females age 18 and over, there were 114.5 males.