The Upper Big Branch Mine is a coal mine located in Montcoal, West Virginia. It was operated by Masontown Coal Company and primarily extracted bituminous coal. The mine was known for its deep underground operations and was part of the larger Appalachian coal mining region. On April 5, 2010, the mine experienced a catastrophic explosion that resulted in the deaths of 29 miners. This tragic event highlighted safety concerns in the coal mining industry and led to investigations by the Mine Safety and Health Administration (MSHA) and other agencies to improve mining safety regulations and practices.