The Union Canal was a towpath canal that existed in southeastern Pennsylvania in the United States during the 19th century. First proposed in 1690 to connect Philadelphia with the Susquehanna River, it ran approximately 82 mi from Middletown on the Susquehanna below Harrisburg to Reading on the Schuylkill River. Construction began in 1792 during the George Washington Administration, but financial difficulties delayed its completion until 1828. Called the "Golden Link," it provided a critical early transportation route for shipping anthracite coal and lumber eastward to Philadelphia. Closed in the 1880s, remnants of the canal remain, most notably the Union Canal Tunnel, a hand-built engineering marvel that is the oldest existing transportation tunnel in the United States. The tunnel is a National Historic Landmark. William Penn's plan for a second settlement in Pennsylvania For a detailed discussion on the 18th century canal that was the predecessor to this canal see this article. The idea of uniting the Schuylkill and Susquehanna rivers by a canal was first proposed and discussed by William Penn in 1690. Penn's plan, conceived a few years after he had founded Philadelphia was to make "a second settlement" on the Susquehanna river, similar in size to that of Philadelphia itself. He made this plan, titled "Some Proposals for a Second Settlement in the Province of Pennsylvania" public in England in 1690. The route envisioned by Penn was a road up the west bank of the Schuylkill to the mouth of French Creek near present-day Phoenixville heading west to the Susquehanna via present day Lancaster and a Susquehanna tributary, Conestoga Creek. Although Penn first proposed the project of continuous water transportation from the Delaware to the Susquehanna, he did not call for the building of a canal. The canal scheme was first proposed by the Society for the Improvement of Roads and Inland Navigation organized in 1789 with preeminent, wartime financier Robert Morris as president, David Rittenhouse, William Smith and John Nicolson. In 1791, the Society presented proposals to the State of Pennsylvania proposing to connect the Atlantic seaboard with Lake Erie. This Pennsylvania plan was before the creation of New York's Western and Northern Inland Lock Navigation Companies in 1792. The New York plan took the first steps to improve navigation on the Mohawk river by constructing a canal between the Mohawk and Lake Ontario but that effort with private financing was insufficient. In the Pennsylvania plan, the