This was once a loop branch that diverted from Southern Pacific's Central Valley main line in Stockton, served ranches in the east valley, and re-connected near Merced.
It was abandoned in stages, generally from south to north. Most of the route ran parallel to local highways. Since the topography was mostly flat, some segments of the right of way have been absorbed into the adjacent farms.
There is a short segment still in service in downtown Oakdale. UP trains reach this segment through trackage rights on the Sierra Railway, which also runs through Oakdale.
Thanks to Mike Palmer for contributing information about this route.