The major infrastructure project of the 20th century that helped connect Appalachian communities to broader U.S. markets is The Appalachian Regional Highway System.

The Appalachian Regional Highway System, developed in the 20th century, was a transformative infrastructure project that helped connect Appalachian communities to broader U.S. markets. By constructing and improving highways across the region, this project reduced isolation and made it easier for goods, services, and people to move in and out of Appalachia. The improved access boosted local economies, fostering trade, tourism, and overall economic development. This highway system played a key role in integrating the region with national markets, providing a vital link for rural communities and contributing to long-term growth and modernization in Appalachia.