South Union is an eastern Logan county community at the junction of US 68 and KY 73. It was established in 1807 by the Society of Believers, or Shakers, soon after Pleasant Hill was established in Mercer county.

At its peak the South Union community covered 6,000 acres and had about 350 members. It was dissolved in 1922. Some of the Shaker's hundreds of buildings are still standing and some, including the large Centre family dwelling, are now part of a museum operated by Shaker Museum at South Union. Another significant surviving structure is a tavern constructed in 1869 on what was then the new railway. Other buildings and grounds are now owned by St. Mark Priory. A South Union post office opened in 1826 and a Shakertown post office operated briefly in 1889.