<P> Youngstown 's economy has been impacted by a loss of the steel industry jobs which started on September 19 , 1977 , on what became known to locals as `` Black Monday '' , and continued into the mid-1980s . While the loss of steel industry jobs in the region coincided with the general deindustrialization of Rust Belt cities such as Youngstown as well as the United States as a whole , Youngstown 's economic struggles have been well documented . In the Mahoning Valley region , where Youngstown is located , the city 's population was halved , while non-industrial businesses were forced to close or relocate due to cascading effects resulting from Youngstown 's deindustrialization . </P>
when did the steel mills closed in youngstown ohio
September 19 , 1977