Columbia subject headings:
Environmental engineering--Middle West.
United States. Army. Corps of Engineers. North Central Division--History.
Harvard subject headings:
Environmental engineering--Middle West.
Environmental engineering--Mississippi River Valley.
Mississippi River Valley--History.
United States. Army. Corps of Engineers. North Central Division--History.
Princeton subject headings:
Environmental engineering--Middle West.
Environmental engineering--Mississippi River Valley.
United States. Army. Corps of Engineers. North Central Division--History.