The Allegheny Portage Railroad was the first railroad constructed through the Allegheny Mountains in central Pennsylvania, United States. It was a series of 10 inclines, approximately long, and operated from 1834 to 1854. It connected two canal divisions of the Main Line of Public Works of the Pennsylvania Canal from Johnstown on the west to Hollidaysburg on the east, thus allowing continuous barge traffic between the Ohio and the Susquehanna rivers. Considered a technological marvel in its day, it played a critical role in opening the interior of the United States beyond the Appalachian Mountains to settlement and commerce. It included the first railroad tunnel in the United States, the Staple Bend Tunnel, and its inauguration was marked with great fanfare.