St. Onge, SD has a population of 34 and is the 28,529th largest city in the United States. The population density is 25 per sq mi which is 134% higher than the South Dakota average and 72% lower than the national average. The median age in St. Onge is 0 which is approximately 100% lower than the South Dakota average of 37. In St. Onge, 100% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 100% of St. Onge residents were born in South Dakota, 0% were born out of state, 0% were born outside of the United States and 0% were foreign born.