For those interested in the early Lincoln Highway, I highly recommend the Ken Burns PBS video and book, Horatio's Drive.  This is the story of the first automobile trip across the country in 1903 before the Lincoln Highway made this possible for all.
Starting on the east coast in New York, the highway moved across the United States before entering California.  In 1915, it passed through the mountains over Donner Pass (current Highway 80),  Lake Tahoe, through the central valley, over the Altamont pass, to Hayward, Oakland's Jack London Square and then via ferry to SF.  The road ends at Lincoln Park in San Francisco near the Legion of Honor.  Today you can find a plaque in Lincoln Park adjacent to the 34th Ave entrance that commemorates the highway.  An alternate route was later added that would follow south of Lake Tahoe and down the highway 50 route.
The Lincoln Highway was the first organized highway to span the United states. Officially started in 1913, it was the dream of the organizers to complete the coast to coast highway in time for the San Francisco Panama Pacific Exposition of 1915.  The highway incorporated many existing roads, improved others and built new sections to try to provide a continuous path for early motorists of the 20th century.   In 1915, some sections were concrete, others where gravel, some dirt and in raining seasons, mud.  The road was improved over the years with better pavement and rerouting of sections to improved the road.
In 1921, the Federal Highway system started to reorganize the nations highway and convert to a system of numbered Highway.  What was the Lincoln highway, was either incorporated into the new system or replaced by new highways.

See the Lincoln Highway Association web site for more on the highway.  They also sell a very nice and very detailed set of maps of the highway route; highly recommended.
Old unpaved roads
Old road being paved
Old road newly paved
Map of approximate route (shown in yellow) of Lincoln Highway in 1915 (Northern route through Truckee).  An alternate route went through South Tahoe.
Hamilton route went through Folsom (green) and then to Auburn.  Lincoln Hwy would go from Sacramento to Newcastle and then to Auburn.
Lincoln Highway route

   Map 86 1/2 San Francisco to Oakland  Includes ferry lines across bay.  (see print)

    Map 86 Oakland to San Jose  Lincoln highway turns at Haywards north of Centerville.  (see print)

    Map 122 Haywards to Byron Hot Spring, Tracy  Includes Dublin, Livermore, Altamont pass. (see print) 

    Map 123 Tracy to Stockton  Includes Banta, Mossdale, Lathrop.  (see print)

    Map 124 Stockton to Galt   Includes Lodi. 
 (see print)

    Map 125 Galt to Sacramento  Includes Elk Grove and "7 mile house".  (see print)

    Map 126 Sacramento to Folsom  Photos of
Capitol, Hotel Land, Perkins, Manlove.  (see print)

    Map 127 Folsom to Auburn   Photo of Freeman Hotel.  (see print)

    Map 128 Auburn to Dutch Flat (Now 80) 
Colfax, Gold Run, Applegate  (see print)

    Map 129 Dutch Flat to Truckee  (Now 80)
Emigrant Gap, snow sheds, Donner Lake. (see print)

    Map 130 Truckee, Tahoe City to Verdi 
Connects with map 129. (see print)

Nevada Lincoln Highway

    Map 131 Reno, Verdi and Steamboat Springs     (see print)

In 1919 Lincoln Highway in Nevada went along  today's Highway 50 to Ely NV and then across Utah to Salt Lake.  The following Hamilton maps closely follow that route

Map 198 Ely to Old Fort Shelborn   (See print)

Map 199 Fort Shelborn to Callao  (See print)

Map 200 Callao to Orr's Ranch  (see print)

Map 201 Orr's Ranch to Salt Lake  (see print)

The 1914 maps of the Hamilton Illustrated Auto Map show many sections of roads that would become incorporated into the California Lincoln highway.   The following set closely follows the route that would become the Lincoln Highway as it traveled from San Francisco, through the central valley, to Donner pass, and on to Verdi Nevada.  

I have  uploaded files to Zazzle to produce large format prints of these maps.  Click on (see print) or go to Zazzle gallery.

Maps from Hamilton's Guide
Photos of the Lincoln Highway route - Past and Present
This photo of the road on the pass above Donner Lake was taken by my grandfather in 1952.  I believe this 1952 road is in the same location as the original Lincoln Highway.  I do not know if they were paving at the time or if the road was partial blacktop and part concrete.  Anyone know?

View detail of road
Donner Lake California - 1952
The Lincoln Highway is gone but you can see it in old photos from around 1915 such as those on this page.   But you can also see  parts of the old route, some little changed, in more recent photos.  
Lincoln Highway east of Reno
Historic Mally's Hotel in Livermore, California around 1914.

Shortly before the opening of the Lincoln Highway. (about 1913)

From Hamilton's Illustrated Atlas
Riverside Hotel in Reno Nevada next to the bridge across the Truckee River.

Around the time of the opening of the Lincoln Highway. (1915)