11870b5d_oric_Significance_Rating__HSR___Description
[HSR] 7 [Examples] Riveted truss bridges with unusual truss configuration (incl. double warren). Older pin-connected truss bridges, and pin-connected truss bridges with remarkable historic integrity. Pre-1900 stone arch bridges. Average concrete curved chord through girders. Movable truss bridges. Pre-1930 cantilever truss bridges. Suspension bridges. [Description] 
These bridges are very important bridges and may predate standardization, or exhibit remarkable design. Generally, bridges at this level will be recognized as historic by the government, but may not be preserved.
HistoricBridges.org - Historic Significance Rating (HSR)
Description