I found this 1991 MA thesis from San Jose State which is quite interesting, free for download on Scholarworks. I was surprised to see I know one of its supervisors:
The development of the Sonora and Mono Wagon Road
David Harmon Johnson
San Jose State University
Just Google the title and you can download the pdf. It has wonderful descriptions but the maps leave much to be desired. The route came from Leavitt Meadows to Fremont Lake before heading up and over. To get around Fremont lake, they had to dig a ditch and drain it a few feet.
The Emigrant Pass Trail was first used 1852 as an alternative to the Carson Pass Trail.
Also found this that clarifies much:
http://www.sonorapassvacations.com/acti ... html#trail
The trail comes down Burst Rock and then Dodge Ridge into what is today Pinecrest, then called Strawberry Camp Ranch.
Relief Valley was a prominent stop on the route, named for a relief expedition.
The approximate route seems to be (from East to West)
1. Leavitt Meadow
2. Fremont Lake
3. Walker Meadows
4. W Fork Walker River
5. Emigrant Pass (BUT NOTE Johnson's thesis: "The Emigrant Pass indicated on the Tower Peak Quadrangle of the US Geological Survey Map is incorrect. The emigrants crossed the summit one mile further north, a half mile northeast of High Emigrant Lake." )
6. Emigrant Meadow Lake
7. Brown Bear Pass
8. Summit Creek: (The Summit Creek gorge was the main reason they decided to abandon the route and build the road over today's Sonora Pass.)
9. Relief Creek/Relief Valley
10. Burst Rock
11. Gianelli Cabin (not named this at the time--the cabin was from the early 1900s)
12. Dodge Ridge. The route followed ridges since they were less forested.
13. Strawberry Camp Ranch (Pinecrest)
From Pinecrest there was an established route to Sonora called the Ice Road. It does not follow the present highway but split the difference between the South Fork of the Stanislaus and the North Fork of the Tuolumne.
Not sure if any of the present hiking trails follow the exact wagon trail or not. Would be interesting to know.
2,375 emigrants used this route in 1853, many with cattle. However, better routes with lesser grades were soon established and by 1854 this route was not much used again. It was basically a 2-year thing for emigrants. Mule trains continued over this route for years to supply miners on the eastern slopes. The main competition was a Placerville--Carson route through the Tahoe area. Eventually the county's main route was built where 108 currently goes--and it was never very successful. The route was finished just as gold mining collapsed.
The emigrants regarded the stretch from Fremont Lake to Relief Camp to be the most difficult part of the journey--and this is the heart of today's wilderness!