Photographer's notes: "Aerial view, April 10, 2012. Note: I was commissioned to photograph over the bridge and dam in April 2012, more than a year after my project was complete." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "Aerial view, April 10, 2012. Note: I was commissioned to photograph over the bridge and dam in April 2012, more than a year after my project was complete." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "Aerial view, April 10, 2012. Note: I was commissioned to photograph over the bridge and dam in April 2012, more than a year after my project was complete." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "View of the highline crane system from the Nevada side looking toward Arizona, March 4, 2009." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "A high line crane system, which ran between the Arizona and Nevada sides of the canyon, was used to transport materials and workers during the bridge's construction." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "Cable stays supported arch construction until the arch was complete. Formwork at the end of the arch segment created the framework for pouring each new concrete section." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "During construction, drivers saw this view as they rounded the Nevada hairpin turn of the old highway. Note: This is one of the few hand held nighttime photographs and the only one taken from a car while in motion. At the time, I did not have permission to stop and photograph from this location." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge