Here are two views of the old Donner Summit - the first by A.J. Russell sometime in the 1860's, and mine from exactly the same spot this past weekend. Note the pre-1925 road in the middle of my photo that does not yet exist in the older one. At the lower right is the eastern entrance to the summit tunnel of the Sierra Nevada - an astounding piece of engineering for the 1860's. It is 1600+ feet long through solid Sierra granite. It took the Chinese laborers more than a year to blast through. 12 inches a day was a good day.
The crews dug a shaft from the surface so that the crews could work in four directions - two crews at either entrance working in, and two crews in the middle working out. The shaft entrance is still there (although obviously sealed for safety reasons.)
Perhaps you have seen the western entrance to the summit tunnel - you pass right by it on the way to the Sugar Bowl Ski Resort. This is circa 1864 folks - the civil war was still raging, and Lincoln was president.
Well, that's all for today. For a great overview of the building of the transcontinental railroad and the fascinating story of how they did it, I recommend, "Nothing Like It In The World" by Stephen Ambrose. They'll talk about how they came right through the Reno area as well.