South Riding, VA has a population of 29,073 and is the 1,472nd largest city in the United States. The population density is 4,248 per sq mi which is 2120% higher than the Virginia average and 4589% higher than the national average. The median age in South Riding is 35 which is approximately 8% lower than the Virginia average of 38. In South Riding, 71% of the population over 15 years of age are married, 62% speak English and 6% speak Spanish. 35% of South Riding residents were born in Virginia, 34% were born out of state, 2% were born outside of the United States and 29% were foreign born.