Before the civil war virgina was united however in 1863 West Virginia chose to become independent which is the most reasonable cause of West Virginia's secession from the rest of the state

West Virginia became a state in 1863 composed of 50 counties of Virginia from the northwest, southwest and Shenandoah areas of western Virginia. 24 of those counties had voted for secession from the United States along with the rest of Virginia. (Richard Curry, "A House Divided", pg 49) Unionists in western Virginia set up a Union state government in Wheeling, and passed an ordinance to create a new state. On Oct. 24, 1861, the ordinance was approved by 18,408 votes. The voting population of the 50 counties from the 1860 census was 79,515. Most of the state was composed of secessionist counties that were included against their will. West Virginia gave approximately 20,000 soldiers to the Confederacy and 20,000 to the Union. (Mark Snell, "West Virginia and the Civil War", pg. 28) The war enabled Unionists to create the state, which would not have been possible in peace time. In 1872 when voting rights were returned to all West Virginians the 1863 Unionist constitution was discarded by popular vote and a new state constitution written and approved that was based on the old Virginia constitution.