Duncan, NE has a population of 484 and is the 19,731st largest city in the United States. The population density is 1,165 per sq mi which is 4760% higher than the Nebraska average and 1186% higher than the national average. The median age in Duncan is 44 which is approximately 23% higher than the Nebraska average of 36. In Duncan, 59% of the population over 15 years of age are married, 96% speak English and 3% speak Spanish. 73% of Duncan residents were born in Nebraska, 27% were born out of state, 0% were born outside of the United States and 0% were foreign born.