Plowden has produced 20 books and his work is held in the permanent collections of the Smithsonian Institution and the Library of Congress.
After working for the Great Northern Railway in 1959, he studied under Minor White and Nathan Lyons, and was an assistant to O. Winston Link and George Meluso.
In 1995, Plowden agreed to transfer the entire archive of his notes, negatives and prints to the Beinecke Rare Book and Manuscript Library at Yale University at the end of his career.
[1] In 2017, the Milwaukee School of Engineering Grohmann Museum exhibited his Steel: The Cycle of Industry collection and repackaged a photo book of the same name, which chronicles steel from its start as taconite pellet mines in Minnesota to the blast furnaces of Gary, Indiana, and from its shipment across the Great Lakes to the demise of the mills in places like Lackawanna, NY.
[2] On his subject matter — steam engines, small town Main Streets, steel mills — Plowden said: "I have always felt that I have been standing in the middle ground between two eras, with one eye on the 19th century and the other on the 21st ... all across America we have left abandoned, like carcasses after the feast, that which only yesterday was state-of-the-art invention.