Apparently Mr. Hepfinger did indeed carve out the spruce log. The final image comes from an auction website that has this description:
Hi Folks, Here we have a nice antique cabinet photo. This is a photo of a hollowed out log on its ways to the 1904 St Louis Worlds Fair. The sign on the log reads, GRAYS HARBOR TOOTHPICK. THE LARGEST TREE EVER HANDLED WORLDS FAIR AT ST LOUIS. WESTERN WASHINGTON EXHIBIT TENT. Where the bars are is titled, ANIMAL DEN. Inside is a Mountain Lion and a Bear. Next room is titled, PIANO ROOM, SOCIAL HALL. Then a sign on the side reads, WE ARE GOING TO MISSOURI AND WE HAVE TO SHOW EM. The photo measures, 5 3/8' by just about 12". Pretty cool antique photograph.
Other photos of this project can be found on websites from Tacoma Public Library, and Washington State University.
William J. Hepfinger was born Dec. 1865 in Ohio to German/Swiss immigrant parents. By 1900 he was living in Aberdeen/Montesano and serving as a deputy sheriff for Chehalis County. In that same year he had taken out a patent for a puzzle map.
For most of his life he made a living as a house painter and interior designer, as well as a novelty salesman. By 1910 he was living in Nebraska and by 1930 in Chicago where he died Apr. 19, 1941. He apparently never married.
Does anyone out there know whatever became of this amazing exhibit?
Addendum:
Got this great email from Ted Tanner of Kenton, Ohio:
"About the spruce log....
I have a postcard that features this log, It seems
after the worlds fair it was given to a senator Palmer of Michigan...After the
property was given to the city and it became a park, this was one of the
attractions along with an old log cabin...the spruce log is mentioned on the
Palmer Park web site under the history page.I find this very interesting having been born and raised in Grays Harbor."
And here's the link:
http://peopleforpalmerpark.org/2012/05/15/history-of-palmer-park/
Thanks Ted!