Arthur, IL has a population of 2,714 and is the 9,332nd largest city in the United States. The population density is 2,059 per sq mi which is 826% higher than the Illinois average and 2172% higher than the national average. The median age in Arthur is 37 which is approximately 2% lower than the Illinois average of 37. In Arthur, 61% of the population over 15 years of age are married, 95% speak English and 1% speak Spanish. 76% of Arthur residents were born in Illinois, 21% were born out of state, 1% were born outside of the United States and 2% were foreign born.