From the Guidebook:
At this place the highway crosses the site of the Old Emigrant Road
which here began a long loop around the Silver Lake basin, taking it to
an elevation of 9,640 feet at one place. This difficult
portion of the road was used by thousands of vehicles
from 1848 to 1863, when it was superseded by a route approximating
the present highway.
Plaque placed by the California State Park Commission in cooperation with the Silver Lake Campers Association