Monroe County is a county located in the U.S. state of West Virginia. As of the 2010 census, the population was 13,502. Its county seat is Union. Monroe County was created from Greenbrier County in 1799 and was named for James Monroe who eventually became the fifth President of the United States.Monroe County was the home of Andrew Summers Rowan of Spanish–American War fame, who is immortalized in Elbert Hubbard's classic A Message to Garcia.