Ajo, AZ has a population of 3,696 and is the 7,795th largest city in the United States. The population density is 111 per sq mi which is 93% higher than the Arizona average and 22% higher than the national average. The median age in Ajo is 48 which is approximately 30% higher than the Arizona average of 37. In Ajo, 56% of the population over 15 years of age are married, 64% speak English and 27% speak Spanish. 59% of Ajo residents were born in Arizona, 32% were born out of state, 1% were born outside of the United States and 8% were foreign born.