Allen is a census-designated place in Bennett County, South Dakota. It has a total area of 3.9 square miles, all of which is land. It is considered to be close to the North American continental pole of inaccessibility.
Educational services and public administration are the major commercial activities here. The closest hopital is the PHS Indian Hospital at Pine Ridge, located about 36 miles away in Pine Ridge. The cost of living here is 23.40% lower than the country average.
This place gets about 18 inches of rain annually. The number of days with measurable precipitation is 70. Snowfall is about 39 inches annually.