Fairfield, AL has a population of 10,937 and is the 3,682nd largest city in the United States. The population density is 3,152 per sq mi which is 3326% higher than the Alabama average and 3379% higher than the national average. The median age in Fairfield is 37 which is approximately 4% lower than the Alabama average of 39. In Fairfield, 44% of the population over 15 years of age are married, 98% speak English and 2% speak Spanish. 89% of Fairfield residents were born in Alabama, 10% were born out of state, 0% were born outside of the United States and 1% were foreign born.