Allen is located in southwest South Dakota. Allen is between the Bennett, Jackson county. Allen has 3.24 square miles of land area and has no water area. As of 2010-2014, the total Allen population is 655, which has grown 56.32% since 2000. The population growth rate is much higher than the state average rate of 10.58% and is much higher than the national average rate of 11.61%. Allen median household income is $15,000 in 2010-2014 and has grown by 97.94% since 2000. The income growth rate is much higher than the state average rate of 42.67% and is much higher than the national average rate of 27.36%. Allen median house value is $9,999 in 2006-2010 and has grown by -73.34% since 2000. The house value growth rate is much lower than the state average rate of 70.48% and is much lower than the national average rate of 46.91%. As a reference, the national Consumer Price Index (CPI) inflation rate for the same period is 26.63%. On average, the public school district that covers Allen is much better than the state average in quality. The Allen area code is 605.