Marietta is a city located in the U.S. state of Georgia. It is centrally within and the county seat of Cobb County. It has a total area of 23.2 square miles at 33°57′12″N 84°32′26″W. The elevation is 1,129 feet above sea level. As of the 2010 census data, it had a total population of 56,579. The population density was 2,551/sq mi. Estimated per capita income in 2016 was $29,157. Marietta has Zip codes 30006-08, 30060-69, and 30090.