Alsip, IL has a population of 19,335 and is the 2,252nd largest city in the United States. The population density is 2,963 per sq mi which is 1233% higher than the Illinois average and 3171% higher than the national average. The median age in Alsip is 33 which is approximately 11% lower than the Illinois average of 37. In Alsip, 48% of the population over 15 years of age are married, 75% speak English and 19% speak Spanish. 78% of Alsip residents were born in Illinois, 8% were born out of state, 1% were born outside of the United States and 13% were foreign born.