This research investigates the influence of layout and design on the severity of trail degradation. Previous trail studies have been restricted by relatively small study areas which provide a limited range of environmental conditions and therefore produce findings with limited applicability; this research improves on this limitation by analyzing a representative sample of the Appalachian Trail with significant ecological diversity. Most trail science studies have also focused on a singular form of trail degradation, whereas this study investigates trail soil loss, widening and muddiness, providing a more cohesive analysis and revealing interrelationships between trail degradation processes. ANOVA testing of the mean values of three trail impact indicators for trail transects within several trail layout frameworks confirms the broad relevance of core trail design principles, specifically the sustainability advantages of trails with low grades and side-hill alignments. Findings also reveal the importance of landform grade in determining the susceptibility of trails to degradation and the influence of routing decisions; these relationships have received relatively little attention in the literature. The results also reveal several methodological considerations for trail alignment metrics and trail impact indicators. / Master of Science / Natural surfaced trails are an essential infrastructure component in parks and protected natural areas. They provide transportation routes through otherwise undeveloped areas and outdoor recreation opportunities for hikers, mountain bikers, and equestrians. Over time, recreational use and natural processes such as rainfall can lead to negative ecological impacts that damage trail treads in ways that impair their utility for visitors and require costly repairs. Environmental factors like unstable soils or extreme precipitation can make trails more susceptible to degradation. However, sustainable trail layouts and effective maintenance can reduce the rate and severity of degradation. This research investigates the influence of trail layout on three chief forms of trail degradation: trail soil loss, muddiness, and widening. Many trail science studies have occurred in small protected natural areas where the limited range of represented environmental conditions reduces the applicability of their findings in dissimilar settings. This study investigates a dataset from a large and ecologically diverse representative sample of the entire Appalachian Trail from Georgia to Maine which significantly broadens the relevance of its findings. Furthermore, many previous trail studies have focused on single forms of trail degradation whereas this study which investigates three, which provides a more cohesive analysis and reveals interrelationships between impacts. Findings confirm the broad pertinence of core sustainable trail design principles, specifically the benefits of low trail grades and side-hill alignments, and suggests that landform grade is an important factor which has received little attention in the literature. The study also revealed several methodological improvements and considerations which may be useful to trail scientists and practitioners.