Danbury, IA has a population of 407 and is the 20,791st largest city in the United States. The population density is 1,005 per sq mi which is 1740% higher than the Iowa average and 1010% higher than the national average. The median age in Danbury is 43 which is approximately 13% higher than the Iowa average of 38. In Danbury, 63% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 83% of Danbury residents were born in Iowa, 17% were born out of state, 0% were born outside of the United States and 0% were foreign born.