Bannockburn, IL has a population of 1,308 and is the 13,520th largest city in the United States. The population density is 645 per sq mi which is 190% higher than the Illinois average and 612% higher than the national average. The median age in Bannockburn is 24 which is approximately 36% lower than the Illinois average of 37. In Bannockburn, 31% of the population over 15 years of age are married, 79% speak English and 5% speak Spanish. 42% of Bannockburn residents were born in Illinois, 42% were born out of state, 1% were born outside of the United States and 15% were foreign born.