On Aug. 4, 1917, at about 7:40 AM, an explosion in the West Kentucky Coal Company's #7 mine shattered the community of Clay. The worst mine disaster in state history was caused by methane gas and an opened-flame headlamp. At the time of the explosion miners were on strike, protesting low wages and dangerous working conditions. Many miners killed were African Americans from the South, employed as strike breakers. Poor record keeping and body condition impaired identification of many of the miners. 153 men were underground. 62 men died. 29 of 47 men identified were buried in unmarked graves in nearby Rock Springs. The #7 mine was located 1.5 miles northwest of Clay.