Mystery Glass Shard Found in Gold Camp

[mtnbay]

Found this amber glass shard in a Gold Rush camp that had activity from the 1850's until 1910 or so. Just a few letters on the shard so it has been a challenge thus far to identify. The letter look like they spell RUS, ROS, HUS or HOS. Any help would be appreciated.

 

[farmdump]

Looks like it might have spelled "U.S.A" at one point. Seems like it could have been part of an old beer bottle or a bitters bottle. Amber glass was first widely used during the Civil War so it could quite possibly be from between the 1860s-1880s. Hope this helped and go back to that site and look for more! if there's one piece of glass, there's more.