The pro-Union population of Trans-Alleghany WV at the time off the Civil War was heavily concentrated in the Ohio Valley. In 1860, Wheeling was a city of over 14,000 people. (Charleston was still a small town of about 1500; all of Raleigh County had about 1700 people in 1860). In 1860, over 1/4 of all the people in what became WV lived in the thin band of Ohio River counties between Hancock and Cabell. But, add in the northern counties of the Mon Valley and surrounding areas, and still only something a little over 1/3 of the people lived in strongly (not unanimously) pro-Union territory.
The population of the Eastern Panhandle counties, Greenbrier and Monroe which were all very strongly pro-secession and wanted to stay with Virginia was around 1/4 of the state in 1860. WV got those counties because the Union subdued and occupied them, not because they wanted to be part of the Union or of WV.
Kanawha was more divided but leaned more Confederate than Union, especially among the "elite;" it was also occupied by Union forces mostly from other states. Much of the early fighting over whether the permanent capitol would be in Wheeling or Charleston was a Blue-Gray political battle, and the "South" obviously won that one.
Less than 120,000 lived in the entire remainder of the state and the population of those areas was divided. No question, many people in WV today are descended from people who joined or were sympathetic to the Confederacy. Of course, given how empty most of Central and Southern WV was at the time of the Civil War and that many people moved to WV after the war was over to work in mines, factories, mills, timbering operations and all the industries that either didn't exist or were very small until well after the war was over, and may of today's Wvians don't even have ancestors who lived here at the time of the war.
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