Williamstown, KY has a population of 3,935 and is the 7,514th largest city in the United States. The population density is 236 per sq mi which is 117% higher than the Kentucky average and 160% higher than the national average. The median age in Williamstown is 36 which is approximately 8% lower than the Kentucky average of 39. In Williamstown, 56% of the population over 15 years of age are married, 97% speak English and 3% speak Spanish. 73% of Williamstown residents were born in Kentucky, 25% were born out of state, 0% were born outside of the United States and 2% were foreign born.