Elizabethton is a city in, and the county seat of Carter County, Tennessee, United States. Elizabethton is the historical site of the first independent American government located west of both the Eastern Continental Divide and the original Thirteen Colonies.The city is also the historical site of the Transylvania Purchase, a major muster site during the American Revolutionary War for both the Battle of Musgrove Mill and the Battle of Kings Mountain. It was within the secessionist North Carolina "State of Franklin" territory.The population of Elizabethton was enumerated at 14,008 during the 2010 census.