 In particular, the Baltimore & Ohio Railroad and the Pennsylvania Railroad were of importance, as well as the Northern Central Railway, which led from Harrisburg to Baltimore, Maryland, and Washington, D.C..The Bethlehem Iron Works produced railroad rails and armor plating for the U.S. Navy's ships.The largest producer of wrought iron artillery pieces for the Union army was the Phoenixville Iron Company in Chester County, which, at its peak, churned out fifty 3" Ordnance Rifles each week.