St. Joe, IN has a population of 467 and is the 19,958th largest city in the United States. The population density is 1,392 per sq mi which is 676% higher than the Indiana average and 1437% higher than the national average. The median age in St. Joe is 23 which is approximately 38% lower than the Indiana average of 37. In St. Joe, 55% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 75% of St. Joe residents were born in Indiana, 23% were born out of state, 1% were born outside of the United States and 1% were foreign born.