This 1920 photo by TC Wohlbruck shows the south fork of The Yuba River below the northern route of The Lincoln Highway at right. This section of the old roadbed is still pretty intact and walkable for being over 100 years old with no upkeep.

The photo below shows the construction of the Highway 80 overpass near Big Bend, in the early 1960s. The road below is Highway 40, complete with thick traffic, part of the reason for the interstate's construction. We can see the earlier Lincoln Highway and overland Emigrant Trail passing under the bridge to the right of the river. Just beyond the bridge is where the first two photos were taken.

The map below shows the location. The blue line is the Lincoln Highway.