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Sagebrush ecosystems in the Great Basin have experienced extensive degradation from exotic invasive plants, altered fire frequency, urban development, climate change, and grazing practices. Feral horses may also negatively influence these ecosystems, but their ecological impact has been investigated in only a handful of studies. We compared vegetation change through time inside and outside of horse management areas (HMAs) in the northwestern corner of the Great Basin by analyzing sagebrush vegetation and soil components derived from Landsat imagery (1985�2016) together with historic (1977�1982; Soil Vegetation Inventory Method) and recent (2011�2016; Assessment Inventory and Monitoring) field plot data collected by the Bureau of Land Management (BLM). Preliminary results suggest that BLM allotments inside of HMAs had a higher abundance of bare ground and a lower abundance of herbaceous and sagebrush cover compared to allotments outside of HMAs across all years. Decreases in bare ground in certain years were accompanied by corresponding increases in herbaceous cover across all allotments. We found significant decreases in the prevalence and proportion cover of native functional groups, and significant increases of exotic functional groups, both inside and outside of HMAs. However, increases of exotic functional groups were particularly large inside of HMAs. We identified the potential drivers (e.g., fires, climatic shifts, grazing, and feral horse and burro use) of observed vegetation changes with multivariate models. This research will provide insight into the causal factors of ecological change in the Great Basin and can inform decisions regarding management of HMAs.