Marietta, MS has a population of 288 and is the 22,707th largest city in the United States. The population density is 162 per sq mi which is 162% higher than the Mississippi average and 79% higher than the national average. The median age in Marietta is 34 which is approximately 8% lower than the Mississippi average of 37. In Marietta, 72% of the population over 15 years of age are married, 94% speak English and 3% speak Spanish. 88% of Marietta residents were born in Mississippi, 10% were born out of state, 0% were born outside of the United States and 3% were foreign born.