Basalt, ID has a population of 391 and is the 20,988th largest city in the United States. The population density is 1,336 per sq mi which is 6902% higher than the Idaho average and 1374% higher than the national average. The median age in Basalt is 36 which is approximately 2% higher than the Idaho average of 36. In Basalt, 69% of the population over 15 years of age are married, 95% speak English and 5% speak Spanish. 83% of Basalt residents were born in Idaho, 16% were born out of state, 0% were born outside of the United States and 2% were foreign born.