Yes to looking things up at the library. You can find quite a bit online, as I did, but I think your best bet may be the map room at the San Jose library. What you really want is the Army or County map for that grid (IIRC it's #18) from around 1940, and the same one from 1900 if you can find it.
Talking to the county government folks can't hurt either. The roads and bridges folks are often their own department, and many - if not most - have records going back a long long time.
OTOH there are several old mines right close to there, and this bridge is neither large nor complex. It is entirely possible that it was made by hand by some guys digging for gold, and then later used by the public perhaps. So there may not be any government record. With the old bridges it's never a sure bet.
Thank you for taking the time to look into this Andrew. It is very much appreciated. Thanks to you and Jason I have learned so much. Next step is visiting both the Nevada and Sierra County libraries and museums. Who knows what I may discover.
After Milton Reservoir was made, and it's pipeline to Bowman Lake, but before Jackson Meadows Reservoir went in (pretty much by damning the end of Pass Creek is my guess), the Henness Pass took a less lofty path SE of Milton Res than it does today. It hooked up with Granitville Road, about where your bridge is. Granitville Road was an extension of what today is called Meadow Lake Road, which meanders all over the place and had several branches back in the day.
Anyway, Henness Pass Road lies North of the headwaters of the Middle Yuba, and Granitville Road comes up South of them, so there has to be a crossing point where two connected. That's your bridge, but then as now, Henness Pass continued off to the East.
See this map:
which is only somewhat useful, because your bridge straddled the Sierra/Nevada county lines in 1955 too.
Aside from finding the GPS location of the bridge at 39.513299,-120.556064 on what Google Maps calls Henness Pass Road, and may have once been (the other end connecting to the dead end road a bit to the NW) but now washed out by the damn spillway.
I'd suggest looking at maps of the Yuba-Bear Project, or of Sierra County before 1963.
Your bridge may date back to Gold Rush days, or it may be built of local materials at any point right up to just before the reservoir project. It does not look serious enough to carry the earth moving vehicles necessary to build the damn, and that's my guess as to the why and when of the "new" Henness Pass/ CR S301 extension.
Questions for the forum:
1. Do you have any information pertaining to the bridge
2. Do you know of another bridge that is similar to this one? If so, where is it located and is it still extant?
Read the article and post your thoughts here: