When WP floated its construction bonds, the buyers stipulated the mainline could not have a ruling grade greater than 1% on the mainline. Prior to the bond issue, the WP had been strongly considering a routing more closely following what is today Highway 50 across central Nevada, but the bond forced them to share the Humboldt River with the long-established SP. The bond language also forced WP to engineer and construct the loop.

As others have noted, the WP originally built a line up through Silver Zone Pass on at least a 3% grade, and the railroad used it until 1913, when the company could finish the engineering of, and then build, the loop. The original grade remained in use for downhill trains for several years after the loop opened. The original grade is fairly obvious on the south side of I-80 as you go through the pass, though it has been obliterated in a couple places by I-80.

As far as getting there...you can either get off I-80 at the Shafter exit and head east along the north side of the interstate, or the Pilot exit and head west. If you do take the Pilot exit, stay on the main dirt road that turns north (away from the interstate) and starts north through Pilot Valley. You want the second decent looking road going towards the west- the first dead ends at a private residence. I think there is one of the Trails West markers at the road junction. High clearance/4WD is recommended. You can take one road that goes up through the middle of the loop, which will give you access to the roads going up towards the head of the loop, or you can find and stay on what was Highway 40, which passes up the bottom of the canyon below I-80. The old cast concrete WESTERN PACIFIC bridge is still in place over old Highway 40, though the lettering is visible only on the west side of the tracks.

Jeff Moore
Elko, NV