#ThisDayInHistory A casinghead gas explosion in Ardmore, Oklahoma, on September 27, 1915, killed 43 people and injured many others. The explosion was triggered by an unidentified source. It destroyed most of downtown Ardmore. The blast was the deadliest and most destructive at that time. Santa Fe Railway paid out more than $1.25 million after 1,700 claims were filed. The tragedy led to new safety laws. (William A. McGalliard Historical Collection at Ardmore Public Library, gateway.okhistory.org)