Franklin, ID has a population of 614 and is the 18,309th largest city in the United States. The population density is 472 per sq mi which is 2371% higher than the Idaho average and 420% higher than the national average. The median age in Franklin is 38 which is approximately 8% higher than the Idaho average of 36. In Franklin, 68% of the population over 15 years of age are married, 87% speak English and 13% speak Spanish. 40% of Franklin residents were born in Idaho, 49% were born out of state, 0% were born outside of the United States and 11% were foreign born.