This concrete edifice is the remains of the Oregon Electric's depot and electrical power substation at Tonquin, Oregon in 1980. At that time, the rail line was operated by the Burlington Northern. This line is now (2004) operated by the Portland & Western Railroad.
The depot section of this structure was in the one-story side. Thanks to J. A. Dobson, Signal Maintainer, Tillamook District, Portland and Western RR for the info. He also says that the book The Northwest's Own Railway Vol 2 by Grande has a good amount of information about these depots/substations.
Location: Tonquin, Oregon
Approximate Coordinates: N45 21.029 W122 47.646