Underwood-Petersville, AL has a population of 3,723 and is the 7,773rd largest city in the United States. The population density is 636 per sq mi which is 591% higher than the Alabama average and 602% higher than the national average. The median age in Underwood-Petersville is 35 which is approximately 10% lower than the Alabama average of 39. In Underwood-Petersville, 66% of the population over 15 years of age are married, 94% speak English and 0% speak Spanish. 74% of Underwood-Petersville residents were born in Alabama, 20% were born out of state, 0% were born outside of the United States and 6% were foreign born.