The single most difficult tunnel along the entire First Transcontinental Railroad was created here. Workers needed to cut through 510m of solid granite. 3-8 hour shifts resulted in an average progress of 0.3 m/day. The effort took so long that construction in Nevada began using trains and machinery delicately hauled over trails. Work on the tunnel not only occurred on both ends, in 1866 a central shaft was cut directly into the middle of the tunnel, so work could occur on four faces at once. Beginning in 1865, the Summit Tunnel did not finish until 1868. Despite all the complications, the four faces connected with only about 5cm differences in the center line.
Donner Pass, Truckee, California

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Make:	NIKON CORPORATION
Model:	NIKON D7000
Exposure:	0.6
Aperture:	f/3.5
ISO Speed:	400
Focal Length:	18 mm
Lens:	18.0-70.0 mm f/3.5-4.5