John J. Endres was a civil engineer. Born in Prussia, he later resided in Cincinnati, Ohio. He designed the Monongahela Incline, the first passenger incline in the United States, in Pittsburgh, Pennsylvania. The incline was originally steam powered and ran on wooden tracks. His daughter, Caroline Endres assisted him on the project. While the two were in Pittsburgh, they met fellow engineer Samuel Diescher. Diescher and John Endres became friends and business partners. Samuel would later marry Caroline, and the two resided in Pittsburgh. Endres returned to Cincinnati after constructing the Monongahela Incline, but he returned to Pittsburgh in 1883 to help Diesher build the Monongahela Freight Incline.