WEST MIFFLIN, Pa. — Beth Hammack, clad in a hard hat and safety glasses, strolled alongside red-hot sheets of metal at U.S. Steel’s Mon Valley Works Irvin Plant last week as she looked to get a sense of how the iconic American company was faring. Hammack, president of the Federal Reserve Bank of Cleveland, regularly tours U.S. companies in an effort to better understand the state of the U.S. economy, and few companies have taken on a more symbolic role than U.S. Steel. Once the quintessential