Pittsburgh-Des Moines Steel Co.
The Pittsburgh-Des Moines Steel Company (originally the Des Moines Bridge and Iron Company), and often referred to as Pitt-Des Moines Steel or PDM was an American steel fabrication company. It operated from 1892 until approximately 2002 when its assets were sold to other companies, including Chicago Bridge & Iron Company. The company began as a builder of steel water tanks and bridges. It also later fabricated the "forked" columns for the World Trade Center in the 1960s, and was the steel fabricator and erector for the Gateway Arch in St. Louis. A number of its works are listed on the National Register of Historic Places. History The company was founded in 1892 by two graduates of Iowa State College, William H. Jackson and Berkeley M. Moss. The partners initially contracted to have their steel tanks fabricated by Keystone Bridge Company of Pittsburgh, but soon took on a third partner, Edward W. Crellin, who was operating a small fabricating shop in Des Moines, Iowa. It was at this point that the Des Moines Bridge and Iron Company was formed. The company would ship steel stock from Pittsburgh for the manufacture of a range of engineered products including water towers, bridges, water