[both St. Ignatius mission historical site brochures]
[both St. Ignatius mission historical site brochures]
St. Ignatius, Montana is a national historic site, "Experience proved the site [along the Pend Oreille River] to be unfavorable. Finally, at the request of the Indians themselves, the Mission was transferred to its present location in 1854
There is nothing to mark this historical location in WA.
And the location is uncertain.