FILE – In this May 19, 1939 file photo, striking union members are guarded by National Guardsmen at the entrance of Harlin-Wallins Coal Corp. property at Verda, in Harlan County, Ky. Kentucky coal miners bled and died to unionize. Their workplaces became war zones, and gun battles once punctuated union protests. The union era’s death knell sounded in Kentucky on Dec. 31, 2014, when Patriot Coal announced the closing of its Highland Mine. (AP Photo/File)