Conley Street Bridge, Road bridge in Deer Lodge, United States

The Conley Street Bridge is a road bridge crossing the Clark Fork River at the western end of Conley Avenue in Deer Lodge. Its design features reinforced concrete beams with vertical sidewalls that run the full length of the span.

Convict labor from the Montana State Penitentiary built the Conley Street Bridge between 1907 and 1912, using reinforced concrete rather than prestressed concrete. It was Montana's first continuous-span reinforced concrete T-beam bridge. The crossing linked Deer Lodge's west side to the Northern Pacific and Milwaukee Road rail yards.

Conley Street was laid out as the route linking Deer Lodge's business district with the Northern Pacific and Milwaukee Road yards, and the bridge carried that traffic over the Clark Fork. Penitentiary crews and freight used the crossing to move supplies between the rail depots and the prison. The 1912 bridge replaced an earlier wooden structure at the same crossing.

The bridge carries vehicle traffic across the Clark Fork River and provides a connection point for those traveling through the western area of town. It remains open and accessible to all vehicles using this crossing.

The bridge's three reinforced concrete T-beam spans rest on concrete piers, and the deck carries the roadway on vertical sidewalls running the full length. It was listed on the National Register of Historic Places, and the Historic American Engineering Record recorded it as survey MT-161.