Williamsville, NY has a population of 5,269 and is the 6,227th largest city in the United States. The population density is 4,188 per sq mi which is 1068% higher than the New York average and 4523% higher than the national average. The median age in Williamsville is 50 which is approximately 30% higher than the New York average of 38. In Williamsville, 50% of the population over 15 years of age are married, 92% speak English and 2% speak Spanish. 77% of Williamsville residents were born in New York, 16% were born out of state, 0% were born outside of the United States and 7% were foreign born.