Grafton, IL has a population of 688 and is the 17,588th largest city in the United States. The population density is 186 per sq mi which is 16% lower than the Illinois average and 105% higher than the national average. The median age in Grafton is 56 which is approximately 50% higher than the Illinois average of 37. In Grafton, 62% of the population over 15 years of age are married, 95% speak English and 2% speak Spanish. 65% of Grafton residents were born in Illinois, 33% were born out of state, 2% were born outside of the United States and 1% were foreign born.