Ketchum, ID has a population of 2,719 and is the 9,320th largest city in the United States. The population density is 848 per sq mi which is 4344% higher than the Idaho average and 836% higher than the national average. The median age in Ketchum is 51 which is approximately 42% higher than the Idaho average of 36. In Ketchum, 46% of the population over 15 years of age are married, 91% speak English and 6% speak Spanish. 22% of Ketchum residents were born in Idaho, 70% were born out of state, 0% were born outside of the United States and 8% were foreign born.