McKeesport, PA, United States
National Tube Works. Incorporated 1869, the works began production here, 1872. By 1901, when it became a subsidiary of U.S. Steel, this was the world's largest pipe producer. Major advances in inspection techniques originated here. Plant operations ceased in 1987.
Listen to the audio guide for Blue plaque № 28398 Free on WIP — starts by itself when you arrive, even with the screen off