Evidence indicates the oldest known structure in the State of Oregon was built by Russians around 1800, which would predate the Lewis and Clark expedition. It is known as the Molalla Log House, and it is situate in the Willamette Valley.
"Unlike typical pioneer construction where chinking was used to fill in gaps in log cabin walls, these logs were hewn to stack so tightly together that there was no need to fill the spaces between them to keep out the weather". *
Splitting of the horizontal members is a problem
Tight-fitting replacement pieces. Superb craftsmanship by Gregg Olson. Half of the structure was replaced.
The southern most known Russian settlement in California is Fort Ross (крепость Россь ), 80 miles or so North of San Francisco.
A Soviet "Russian America" stamp from 1991.