Sioux Falls, SD has a population of 167,884 and is the 151st largest city in the United States. The population density is 2,178 per sq mi which is 20045% higher than the South Dakota average and 2304% higher than the national average. The median age in Sioux Falls is 34 which is approximately 7% lower than the South Dakota average of 37. In Sioux Falls, 54% of the population over 15 years of age are married, 90% speak English and 4% speak Spanish. 60% of Sioux Falls residents were born in South Dakota, 33% were born out of state, 1% were born outside of the United States and 7% were foreign born.