Marion, IN has a population of 28,698 and is the 1,493rd largest city in the United States. The population density is 1,842 per sq mi which is 880% higher than the Indiana average and 1933% higher than the national average. The median age in Marion is 36 which is approximately 5% lower than the Indiana average of 37. In Marion, 44% of the population over 15 years of age are married, 96% speak English and 2% speak Spanish. 68% of Marion residents were born in Indiana, 29% were born out of state, 1% were born outside of the United States and 2% were foreign born.