Depue was the president of the Central Steel Tube Company in Clinton, Iowa when he opened a small factory in Maquoketa to manufacture machine gun components during World War II.

He expanded the operation calling it The Maquoketa Company, and built a factory on the east side of town.

Clinton Machine Company manufactured small gasoline engines, and by 1956 they were the tenth largest employer in Iowa.

However, the Charnay Group failed to adequately support Clinton Engines financially, and it had to file for bankruptcy the same year.

Clinton Engines was sold to Martin Hoffinger, a New York investor, who operated the company on a reduced basis.

The Jackson County Historical Society maintains the Clinton Engines Museum, the Jackson County Research & Family History Library, the JCHS Media Arts Center, the Clinton Engines Association, and a large program center in the building.