As a practical conveyance during the horse-and-buggy era, the Monongahela Incline was one of seventeen built and operated in Pittsburgh in the last century. Of the seventeen, the Monongahela and the Duquesne are the only two remaining operating units. While the Mt. Washington Incline was known as a coal-carrying incline plane in 1854, the Monongahela Incline is probably the earliest passenger-carrying incline in the United States and has been in continuous successful service since its construction.
Designed by Sam Diescher, son-in-law of the Monongahela's designer John Endres, the Duquesne Incline opened May 20, 1877, as the second of seventeen built and operated in the Pittsburgh area. It has operated with only minor interruptions for the last one hundred years. A preservation group from Duquesne Heights and Mount Washington interceded in 1962 to refurbish this incline to working order. Like the Monongahela, the Duquesne was steam powered and then converted to electric and updated with modern safety devices.