There are 8 US Post Offices in Mineral County serving a total of 28,920 residents equating to 3,615 residents per post office. It's estimated that approximately 46,160 packages are handled across the 8 county post offices annually. Mineral County is a county located in the U.S. state of West Virginia. It is part of the Cumberland, MD-WV Metropolitan Statistical Area. As of the 2010 census, the population was 28,212. Its county seat is Keyser. The county was founded in 1866. Mineral County is included in the Cumberland, MD-WV Metropolitan Statistical Area."