Near‐field surface displacement measurements allow us to quantify the on‐ and off‐fault proportion of earthquake‐related deformation. The Hebgen Lake earthquake was a large normal event with a complex surface rupture, which broke across mountainous terrain. This study takes advantage of high‐resolution historical aerial stereo‐imagery to measure three‐dimensional displacement from correlation of the orthorectified pre‐ and post‐earthquake image mosaics. The results reveal new strike‐slip ruptures which are possibly associated with the aftershocks from 18th August 1959. These structures likely reflect internal block deformation induced by the complex geometry of the mainshock. Additionally, comparison of our results with the existing displacement data shows that the optical image correlation‐derived offsets often exceed the field measurements by >50%. We attribute this difference to inelastic off‐fault deformation. Plain Language Summary: This study quantifies the surface deformation created by the 1959 Hebgen Lake earthquake. To measure the displacement field we use optical image correlation (OIC). OIC compares the pixel locations in the pre‐earthquake and post‐earthquake image and calculates any displacement from the pixel‐shift. The images cover a large area, which enabled us to find new fault ruptures that slipped between 1947 and 1977. We also measured the displacement everywhere along the Red Canyon fault. Our displacement estimates are twice as large as those measured in the field. We think this is because our values capture diffuse displacement away from the main fault, whereas the field measurements only reveal the localized component of displacement on the fault plane. This study aims to improve understanding of how fault ruptures distribute slip into their surroundings, which in turn has important implications for how we assess their seismic hazard. Key Points: Measurement of three‐dimensional surface displacement field produced by extensional dip‐slip earthquakeApplication of optical image correlation to historical aerial imagery, thus expanding the window of remote geodetic observationDetection of previously unrecognized surface ruptures probably associated with the 1959 Hebgen Lake earthquake [ABSTRACT FROM AUTHOR]