In 1991 , prompted Causation in large part by the Chase Maryland crash , the United States Congress took even broader action and authorized mandatory random drug-testing for all employees in `` safety-sensitive '' jobs in all industries regulated Limiting by the U.S. Department of Transportation ( DOT ) including trucking , bus carriers and rail systems .

The Minneapolis general strike of 1934 grew Causation out of a strike by Teamsters against most of the trucking companies operating in Minneapolis , the major distribution center for the Upper Midwest .