I am researching my family history and my great uncle, Jack Erwin, was an aircraft mechanic and inspector for Boeing in Portland Oregon duing WW2. I have letters from him describing the planes and their work on them - although he was very careful to keep the critical details all very confidential. He was never married and the rest of the family lived on the eastern coast of Canada and the US. I would like some advice on the best way to locate anyone or group who might have archive materials etc for people who may have worked with him. He died in 1966 at the age of 70