There are 3 US Post Offices in Jefferson County serving a total of 8,428 residents equating to 2,809 residents per post office. It's estimated that approximately 13,452 packages are handled across the 3 county post offices annually. Jefferson County is a county located in the U.S. state of Mississippi; its western border is formed by the Mississippi River. As of the 2010 census, the population was 7,726, making it the third-least populous county in Mississippi. Its county seat is Fayette. The county is named for U.S. President Thomas Jefferson. Originally developed as cotton plantations in the antebellum era, the rural county has struggled with a declining economy and reduced population since the mechanization of agriculture and urbanization of other areas. In 2014 its estimated population of 7599 was roughly one-third of the population peak in 1900. Within the United States, in 2009 rural Jefferson County had the highest percentage of African Americans of any county. It was the fourth-poorest county in the nation."