The union era's death knell sounded in Kentucky on New Year's Eve, when Patriot Coal announced the closing of its Highland Mine. The underground mine in western Kentucky employed about 400 hourly workers represented by the United Mine Workers of America. ... Union membership remains substantial in West Virginia, with more than 30,000 members, largely because that state wasn't affected by the environmental regulations on high-sulfur coal that essentially halted mining in western Kentucky in the 1990s. Smith said those western Kentucky mine shutdowns led to the loss of about 20,000 union members in two years.