The CR&NW had a 300-350 ft. tunnel approximately 7 miles north of the Tasnuna Bridge. Sources disagree as to the exact milepost, although the “Draft Supplement to the Copper River High Final Environmental Impact Statement”, page 54, places it at 88.0. This document is more consistent with railroad mileposts, so I’m placing it at 88.0.

Suspected location:
Acme Mapper

Sources

1: “Report of Archeological and Historical Investigations along the Copper River, Tasnuna River to Chitina to the Deptartment of Highways” Reger, Douglas; Cole, Terrence; Brown, Michael. Prepared for Alaska Division of Parks, Office of Statewide Cultural Programs, July 1975

2: “Draft Supplement to the Copper River High Final Environmental Impact Statement” Nov 3, 1976