For decades, the Appalachian Development Highway System (ADHS) has been viewed as one of the most significant long-term infrastructure investments supporting economic opportunity in Appalachia.

With more than 92% of the system now open to traffic, this study, commissioned by the Appalachian Regional Commission, examines the economic development impacts of completed ADHS corridors. It does so through detailed case studies of:

• Corridor B (US-23) in eastern Kentucky
• Corridor E (I-68) in western Maryland
• Corridor T (I-86) in southern New York
• Corridor V in Alabama and Mississippi

Across the case studies, the evidence shows that ADHS corridors provide a foundational enabling condition for economic development. By reducing travel times, improving freight efficiency, expanding labor market commuting sheds, and connecting communities to larger markets, the corridors have supported manufacturing, logistics, and tourism activity that would otherwise be difficult to realize in rural Appalachia.

At the same time, the study finds that highway investment alone may not be sufficient to transform regional economies or generate large gains in population or employment. Instead, infrastructure enables opportunity, with outcomes depending on complementary factors such as workforce readiness, site preparedness, economic development strategy, and multimodal transportation connectivity.

The findings highlight the importance of highways in industrial competitiveness, with high-quality access often a prerequisite in site selection decisions. Improved connectivity also supports broader economic performance through higher-quality jobs, stronger wages, and increased resilience.

Overall, the ADHS has contributed to economic development less as a singular driver of growth than as a platform for growth, with the greatest impacts realized where highway access aligns with strategic assets, including industrial sites, multimodal transportation networks, and proactive development efforts.