I believe your are right, although I recall there may be one or two company town in western Oregon and Washington that managed to survive. I suspect it was because other industries came in to provide jobs.
In Eastern Oregon, Seneca was a company town dependent on Edward Hines and the Oregon and Northwestern RR for jobs. Although in later years there were other small lumber companies as well. Now however, it is populated largely by retired folks and a few folks working in Burns or John Day. The homes closest to the highway were constructed by Hines for bosses, superindents and the locomotive crews. However, I think they were purchased from the company. All the other homes were privately owned. While I lived there many of the homes had been camp cars at one time. I remember looking beneath one of the homes and seeing the structure of a box car less trucks.
The elementary school in Seneca that I attended and graduated from in 1950 is still in use. It is a brick structure with a wood construction wing added and in use when I went to school there. While I was in the 7th grade a quonset type structure was built as a gymnasium, and that is also still in use.
dan