There are 7 US Post Offices in Dillon County serving a total of 32,809 residents equating to 4,687 residents per post office. It's estimated that approximately 52,367 packages are handled across the 7 county post offices annually. Dillon County is a county located in the U.S. state of South Carolina. As of the 2010 census, the county's population was 32,062. The county seat is Dillon. Founded in 1910 from a portion of Marion County, both Dillon County and the city of Dillon were named for prosperous local citizen James W. Dillon (1826-1913), an Irishman who settled there and led a campaign to bring the railroad into the community. The result of this effort was the construction of the Wilson Short Cut Railroad, which later became part of the Atlantic Coast Line Railroad, and which brought greater prosperity to the area by directly linking Dillon County to the national network of railroads."