In 1983, about 36 km of the 130-km-long Lost River fault zone (LRFZ) in the Basin and Range Province ruptured in the M 6.9 Borah Peak earthquake. The greatest normal-faulting displacement (~2 m) occurred along the 24-km-long Thousand Springs section of the fault, but surface rupture extended north, across a prominent bedrock ridge that forms a structural boundary with the adjacent 16-km-long Warm Springs section. Understanding this rupture in the context of the structural complexity of the LRFZ is important to the characterization of multi-segment normal faults globally. Our investigation is focused on two issues: (1) what is the distribution of 1983 displacement on the Warm Springs and Thousand Springs sections and how does it compare to prehistoric slip on the LRFZ, and (2) what does the 1983 surface rupture imply about rupture boundaries along the LRFZ? To address these questions, we acquired low-altitude aerial photographs and used image-based (structure-from-motion) modeling to generate 5–10-cm digital surface models for the northern part of the 1983 rupture. We document at least 9 km of normal-fault rupture on the Warm Springs section, including a previously unrecognized, ~1-km-long fault splay. Using these surface models, we have remapped the northern end of the 1983 surface rupture and collected a new, high-density suite of along-strike displacement measurements. We compare these results to surface-offset measurements for prehistoric scarps along the LRFZ and Holocene earthquake displacements observed in unpublished paleoseismic trenches excavated shortly after the 1983 earthquake. We have also developed a protocol for measuring scarp offsets in complex normal-faulting environments and tools for partially automating displacement measurements. These data will allow us to evaluate the segmentation of the LRFZ, the significance of the 1983 multi-section rupture, and the value of displacement data in reconstructing the style and extent of prehistoric ruptures.