There are 8 US Post Offices in Newton County serving a total of 26,411 residents equating to 3,301 residents per post office. It's estimated that approximately 42,155 packages are handled across the 8 county post offices annually. Newton County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 21,720. Its county seat is Decatur.