Southside, AL has a population of 8,563 and is the 4,433rd largest city in the United States. The population density is 451 per sq mi which is 365% higher than the Alabama average and 398% higher than the national average. The median age in Southside is 43 which is approximately 12% higher than the Alabama average of 39. In Southside, 71% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 80% of Southside residents were born in Alabama, 17% were born out of state, 0% were born outside of the United States and 3% were foreign born.