Probably more likely that excess rail was relaid in other places rather than being melted down.

Why waste valuable labor melting it down when it could be used "as-is" to aid the war effort? (Maybe the original poster would have included this as "donated.")

On a related note, three interurban systems in the Bay Area (Sacramento Northern, NWP, and the IER) ceased passenger operations just WW II. Lots of their equipment was re-used in other areas as part of the war effort.

Also, about 80 old New York elevated railway cars were rescued from the scrap line and sent to the Bay Area to transport shipyard workers. A lot of other recycled material was used to construct the Shipyard Railway from Oakland to the new Kaiser Shipyard in Richmond.