Hi. I would think that, if the older passport on which the US visa is printed, was valid within the last 5 years, the older passport also should be scanned. if that passport was not valid within the last 5 years, then its probably not needed. i would consider the PR card as a travel document here, as travel for a permanent resident would require it to be presented; however "travel documents" usually refers to passport replacements (eg emergency certificates, refugee documents, etc). that being said, the Canadian authorities are fans of full disclosure. It shows to them that you are being completely honest, transparent and possess full integrity. If you give twice to three times the number of documents they`ve requested, chances are that your application goes smoother. All the best!