Humboldt, SD has a population of 719 and is the 17,303rd largest city in the United States. The population density is 1,161 per sq mi which is 10644% higher than the South Dakota average and 1182% higher than the national average. The median age in Humboldt is 36 which is approximately 3% lower than the South Dakota average of 37. In Humboldt, 72% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 66% of Humboldt residents were born in South Dakota, 33% were born out of state, 0% were born outside of the United States and 1% were foreign born.