Mon–Fayette Expressway

The Mon–Fayette Expressway is a partially-completed controlled-access toll road that is planned to eventually link Interstate 68 near Morgantown, West Virginia with Interstate 376 near Monroeville, Pennsylvania. The ultimate goal of the highway is to provide a high speed north–south connection between Morgantown and the eastern side of Pittsburgh while revitalizing economically distressed Monongahela River Valley towns in Fayette and Washington counties, serving as an alternative to Interstate 79 to the west, as well as relieving the PA 51 alignment from Pittsburgh to Uniontown.

Although it is being built to Interstate Highway standards, there is debate as to whether or not the freeway will become part of the Interstate Highway System. At least one proposal was to give it the Interstate 97 designation (unrelated to the existing I-97 in Maryland), while others have been to make it a spur route of I-68. In the interim, the highway uses state highway designations instead, as it does not parallel an existing U.S. Route for its entire length, though it does parallel and at times run concurrent with U.S. Route 40 and U.S. Route 119 for portions of its length. The route, in its three jurisdictions, uses the number 43 for familiarity, and is thus known as West Virginia Route 43 (WV 43), Pennsylvania Route 43 (PA 43), and PA Turnpike 43. Most of the route is maintained by the Pennsylvania Turnpike Commission, while the Pennsylvania Department of Transportation maintains small portions of the highway near Uniontown, and the West Virginia Division of Highways maintains the short section in West Virginia. Despite the numerous agencies overseeing the highway, it is one continuous highway.

South of Jefferson Hills, the Mon–Fayette Expressway is complete. Construction to complete the highway to Duquesne began on May 22, 2023, with plans existing to extend the road further to Monroeville.