Joseph Yablonski was born on 3 March 1910 in Pittsburgh, Pennsylvania, USA. He was married to Margaret. He died on 31 December 1969 in Clarksville, Pennsylvania, USA.
He was a member of the executive board of the United Mine Workers of
America. He was murdered, along with his wife Margaret and daughter
Charlotte, on New Year's Eve 1969 (the bodies were found days later)
after an unsuccessful campaign for the union presidency. Union
president Tony Boyle was later convicted of ordering the murders.