Boise, ID has a population of 218,677 and is the 100th largest city in the United States. The population density is 2,667 per sq mi which is 13880% higher than the Idaho average and 2844% higher than the national average. The median age in Boise is 36 which is approximately equal to the Idaho average of 36. In Boise, 52% of the population over 15 years of age are married, 90% speak English and 5% speak Spanish. 44% of Boise residents were born in Idaho, 47% were born out of state, 1% were born outside of the United States and 7% were foreign born.