Allison, IA has a population of 1,222 and is the 13,923rd largest city in the United States. The population density is 417 per sq mi which is 663% higher than the Iowa average and 360% higher than the national average. The median age in Allison is 35 which is approximately 8% lower than the Iowa average of 38. In Allison, 59% of the population over 15 years of age are married, 93% speak English and 1% speak Spanish. 79% of Allison residents were born in Iowa, 16% were born out of state, 0% were born outside of the United States and 5% were foreign born.