Marietta is a village in Fulton County, Illinois, United States. The population was 112 at the 2010 census, down from 150 at the 2000 census.Marietta is located in western Fulton County at 4030?5?N 9023?35?W? / ?40.50139N 90.39306W? / 40.50139; -90.39306, along Illinois Route 95, which leads east 11 miles to Cuba and west 6 miles to Illinois Route 41 at a point 5 miles south of Bushnell.According to the 2010 census, Marietta has a total area of 0.27 square miles, all land.As of the census of 2000, there were 150 people, 56 households, and 40 families residing in the village. The population density was 557.0 people per square mile. There were 59 housing units at an average density of 219.1 per square mile. The racial makeup of the village was 98.67% White and 1.33% Native American.There were 56 households out of which 32.1% had children under the age of 18 living with them, 62.5% were married couples living together, 7.1% had a female householder with no husband present, and 26.