Galesburg, IL has a population of 31,469 and is the 1,355th largest city in the United States. The population density is 1,774 per sq mi which is 698% higher than the Illinois average and 1858% higher than the national average. The median age in Galesburg is 40 which is approximately 6% higher than the Illinois average of 37. In Galesburg, 45% of the population over 15 years of age are married, 93% speak English and 4% speak Spanish. 76% of Galesburg residents were born in Illinois, 19% were born out of state, 0% were born outside of the United States and 4% were foreign born.