Union is a town in Monroe County, West Virginia, United States. Union’s population is 427 as of 2020. It is the county seat of Monroe County. Monroe County was established by an act of the Assembly of Virginia on January 14, 1799, occupying land formerly a part of Greenbrier County. Union did not yet exist when the county's first court convened in 1799…Union is a town in Monroe County, West Virginia, United States. Union’s population is 427 as of 2020. It is the county seat of Monroe County. Monroe County was established by an act of the Assembly of Virginia on January 14, 1799, occupying land formerly a part of Greenbrier County. Union did not yet exist when the county's first court convened in 1799. However, shortly after Monroe County was created, James Alexander offered 25 acres of land, including a lot for a courthouse which in time became the town of Union. On January 6, 1800, the Virginia Assembly passed an act creating the town of Union and naming William Haynes, John Gray, John Byrnside, James Handley, Michael Erskine, John Hutchinson, and Isaac Estill trustees.