Shellsburg, IA has a population of 1,097 and is the 14,568th largest city in the United States. The population density is 1,432 per sq mi which is 2520% higher than the Iowa average and 1480% higher than the national average. The median age in Shellsburg is 43 which is approximately 12% higher than the Iowa average of 38. In Shellsburg, 65% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 81% of Shellsburg residents were born in Iowa, 18% were born out of state, 0% were born outside of the United States and 0% were foreign born.