Smithdale is a small unincorporated community in Amite County, Mississippi, United States, located 13 miles from the county seat of Liberty. The zip code for Smithdale is 39664; the community has a post office (founded in 1828). Major highways in Smithdale are Mississippi State Route 569, Mississippi State Route 570 and U.S. Route 98. Smithdale stretches over parts of four counties, including Amite, Pike, Lincoln, and Franklin counties. The community is part of the McComb, Mississippi Micropolitan Statistical Area.