As promised, more information on the Richfield enigma, courtesy of this morning's Oregonian:
The Richfield (oil company) sign: Lots of people were able to help S.H. of Southwest Portland, who wrote, "I've been trying for years to find someone who can tell me where in the West Hills the old Richfield sign was located."
That sign reportedly was the biggest electrical sign in North America in the 1930s. It was 725 feet long and 60 feet high, readable for 10 miles, and visible for 50 miles. It was installed in 1928 in Healy Heights on a ridge. It was on until 1931, when Richfield went into bankruptcy, switched on again in 1933. The plug was pulled for good in the late 1930s, according to E. Kimbark MacColl's 1979 book, "The Growth of a City, Power and Politics in Portland, Oregon 1915 to 1950."
Several readers remember it, including Lewis McArthur (of "Oregon Geographic Names," who lived two blocks from it); N.R.B. of Southwest Portland, who remembered a walkway up there; and J.C., of Northwest Portland, who said the best view was from the east side. J.T. of Portland Heights pointed out the MacColl book; G.H. says the sign was at the extreme south end of Southwest Council Crest Drive, just north of where the KGON radio tower now stands. It covered several lots and the footings for the sign may still be there.
S.P., an OHSU librarian, has an old glass lantern slide of it; and The Oregonian's history columnist, John Terry, wrote a column about it in 2001, in a response to a woman with the same question.
There were other, smaller, Richfield signs: B.T. of Southwest Portland remembers one on Northeast 12th Avenue and Sandy Boulevard. Al from North Portland and "Old Old Timer" remember one right before the bridge at Jantzen Beach and one at the intersection of highways 99E and 99W in the heyday of the Jantzen Beach amusement park.
See the entire Back Fence column online at OregonLive.com.
I think our glass lantern slide does add some information to this history: clearly, the sign was still up on the hill and in good condition circa 1940, when the Library/Auditorium building was originally constructed. It was only two years later, in February 1942, when Richfield's Elwood Field in California was shelled by a Japanese submarine, making Richfield the "first victim of attack by foreign power on U.S. soil since War of 1812," according to the ARCO company history web page.
UPDATE, 3/3/2017: A user recently inquired about this image, and I discovered that it's since been digitized. You can view the slide featuring this sign here via OHSU Digital Collections: https://www.ohsu.edu/custom/library/digital-collections/items/show/13315