Developed by the Pennsylvania Steel Company in 1887-91, the Sparrows Point steel plant and shipyard were purchased by Bethlehem Steel in 1916 and grew to become the largest in the world. They were a vital supplier of steel and ships during both World Wars and produced steel used in the Golden Gate Bridge and the Empire State Building. By 1960 the plant stretched four miles long and employed more than 30,000 workers, many of whose families lived in the company town. The plant closed in 2012.