Photographer's notes: "The dirt road leading from the Lower Access Road to the Hoover Dam Police shooting range plays off of the arch formed by the bridge construction, June 30, 2009." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "View upstream of the bridge and dam. The position of the green boom indicates a concrete pour for the arch was in progress. Note: This is one of the few photographs where I supplemented existing light by adding a flash to give the hill on the left detail." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "Sunrise, looking across the canyon to Nevada. The arch was nearly complete with temporary pylons and cable stays supporting each segment. The highline crane system prepared to lower a rebar section into position." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "Workers arriving to work via the highline crane and manbasket, July 1, 2009." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "View from the Arizona pylons toward arch construction and Nevada. The cable stays were covered in white in reduce expansion and contraction from the desert sun and heat. Note: This was the only evening I was allowed on top of the temporary pylons to shoot." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "On the end of the Nevada arch segment, ironworkers prepared formwork prior to pouring the next concrete section, July 1, 2009." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge

Photographer's notes: "On the end of the Nevada arch segment, ironworkers prepared formwork prior to pouring the next concrete section. Note: This was the only evening I was allowed on top of the temporary pylons to shoot." Site Name: Mike O'Callaghan-Pat Tillman Memorial Bridge