| 1828 |
Construction began on the C & O Canal, following the route of the Potomac River north. Original plan was to go to the Ohio River in Pittsburgh, Pennsylvania. |
| 1850 |
C & O Canal construction stopped at Cumberland, Maryland 184.5 miles from Washington, DC. The canal operated as a transportation route, primarily hauling coal from western Maryland to the port of Georgetown in Washington, DC. |
| 1877 | The Montour Railroad was first chartered. |
| 1883 | Pittsburgh, McKeesport & Youghiogheny Railroad (PMc&Y) opens section of railroad between cities of Connellsville and McKeesport. Several changes in ownership, but section remains active railroad for over 100 years. |
| 1924 | C & O Canal closed as transportation route. Hundreds of original structures, including locks, lockhouses, and aqueducts, serve as reminders of the canal's role as a transportation system during the Canal Era. |
| 1938 | Corridor acquired by the Federal Government for $2 million. Plans for super highway evolved. |
| 1946 | The Montour Railroad was jointly sold to the Pennsylvania Railroad and the Pittsburgh and Lake Erie Railroad. |
| 1950s |
Justice William O. Douglas opposed plans to use the C & O Canal corridor to construct a super highway into Maryland. He recognized the historical, cultural, geological, and botanical significance of the C & O and he challenged opinion-shapers of his day to walk the length with him and decided for themselves if it should be destroyed. |
| 1954 | Justice Douglas leads the walk and gains support which resulted in the formation of the C & O Canal National Park. |
| 1961 |
C & O Canal named a national monument |
| 1962 | Trains stopped running on the Peters Creek Branch of the Montour Railroad. |
| 1971 |
Chesapeake and Ohio Canal Historical Park designated. |
| 1972 | The Western-Maryland Railroad through Somerset County was abandoned. |
| 1975 | Western PA conservancy acquired the Western Maryland right of way for Ohiopyle State Park. |
| 1984 | The Montour Railroad was abandoned leaving 55 miles of railroad vacant. |
| 1986 | 9.5 mile rail-trail conversion project in Pennsylvania's Ohiopyle State on Western Maryland railbed is completed. Immediate success of the first stretch of the Youghiogheny River Trail. |
| 1987 | The President's Commission on America's Outdoors recommended that "communities create a network of greenways across the country... and states establish scenic byways." |
| 1989 | The Montour Trail Council was organized. |
| 1990 | P&LE files to abandon McKeesport to Connellsville corridor. Interest in railbanking from three counties involved: Allegheny, Westmoreland, and Fayette and a Youghiogheny River Trail Task Force was formed to study the feasibility of converting the P&LE Railroad right of way into a recreational trail. |
| 1992 |
Trail construction begins on the Youghiogheny River Trail(North). The initial section of the Montour Trail (four miles in Cecil Township in Washington County) opened. |
| 1995 |
Allegheny Trail Alliance formed as a unique alliance of the seven groups building trails from Pittsburgh to Cumberland, Maryland. |
| 1996 | Master Implementation Plan for completing the Pittsburgh to Cumberland Trail System undertaken. Department of Conservation and Natural Resources Secretary John C. Oliver recognizes the trail as one of the most important rail trail projects in the United States. |
| 1997 | $16 million included in Pennsylvania's Capital Budget through efforts of Representative Rick Geist. Last section of right of way for the Allegheny Highlands Trail acquired. |
| 1998 | Governor Tom Ridge releases $1.5 from the capital budget for the Allegheny Trail Alliance. Federal Transportation Bill is signed and includes six million dollars in TEA-21 monies for the Allegheny Trail Alliance. During Keystone Ride 98, Governor Tom Ridge officially opens the Smithton to Dawson section of the Youghiogheny River Trail linking Confluence to Boston, over 66 miles of completed trail. |
| 1999 | First annual Yockatomac Trek -- Washington to Pittsburgh Group Ride. |
| 2000 | Three bridges opened! |
| 2001 | Fort Hill to Confluence section completed--linking McKeesport to the end of the Salisbury Viaduct via 100 miles to continuous trail. |
| 2003 | Keystone Viaduct and Big Savage Tunnel rehabbed for trail use. |
| 2004 | Five miles opened in Maryland from State Line to Frostburg. |
