Clayton, DE has a population of 3,080 and is the 8,678th largest city in the United States. The population density is 1,614 per sq mi which is 338% higher than the Delaware average and 1681% higher than the national average. The median age in Clayton is 31 which is approximately 21% lower than the Delaware average of 40. In Clayton, 62% of the population over 15 years of age are married, 89% speak English and 7% speak Spanish. 57% of Clayton residents were born in Delaware, 38% were born out of state, 1% were born outside of the United States and 4% were foreign born.