While highway underpasses and culverts are often identified in conservation planning as wildlife corridors, their success at facilitating connectivity in deserts has rarely been tested. We evaluated wildlife use of seven, pre-existing highway underpass structures and four associated canyon sites over 29 mo to identify spatial and temporal wildlife use patterns and to assess factors that may constrain wildlife use, particularly for native carnivore species. Our results indicate that a wide diversity of wildlife species utilize the underpass structures including rodents, lagomorphs, deer, and carnivores. Structural attributes of the underpasses have a minor influence on use by most observed species, although structural characteristics and human activity both contributed to determining bobcat (Lynx rufus) usage. Wildlife and human diel patterns differed between the underpass sites and their associated canyons. We suggest that providing a range of underpass structures to support use by a diversity of wildlife, as well as development or modification of underpasses to minimize human disturbance, will enhance landscape connectivity in desert systems.