McCook, IL has a population of 226 and is the 23,901st largest city in the United States. The population density is 86 per sq mi which is 61% lower than the Illinois average and 5% lower than the national average. The median age in McCook is 34 which is approximately 10% lower than the Illinois average of 37. In McCook, 48% of the population over 15 years of age are married, 81% speak English and 11% speak Spanish. 79% of McCook residents were born in Illinois, 11% were born out of state, 1% were born outside of the United States and 10% were foreign born.