Herndon, VA has a population of 24,415 and is the 1,785th largest city in the United States. The population density is 5,695 per sq mi which is 2876% higher than the Virginia average and 6186% higher than the national average. The median age in Herndon is 35 which is approximately 8% lower than the Virginia average of 38. In Herndon, 55% of the population over 15 years of age are married, 45% speak English and 32% speak Spanish. 28% of Herndon residents were born in Virginia, 28% were born out of state, 2% were born outside of the United States and 41% were foreign born.