Humboldt, IA has a population of 4,602 and is the 6,835th largest city in the United States. The population density is 996 per sq mi which is 1723% higher than the Iowa average and 999% higher than the national average. The median age in Humboldt is 42 which is approximately 9% higher than the Iowa average of 38. In Humboldt, 64% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 76% of Humboldt residents were born in Iowa, 20% were born out of state, 1% were born outside of the United States and 3% were foreign born.