Allison, PA has a population of 546 and is the 19,035th largest city in the United States. The population density is 817 per sq mi which is 195% higher than the Pennsylvania average and 801% higher than the national average. The median age in Allison is 47 which is approximately 16% higher than the Pennsylvania average of 41. In Allison, 81% of the population over 15 years of age are married, 96% speak English and 0% speak Spanish. 90% of Allison residents were born in Pennsylvania, 10% were born out of state, 0% were born outside of the United States and 0% were foreign born.