This is a low-res scan of a 52-minute "home movie" which was shot on professional 16mm film, not the usual 8mm. This is a section of a much longer film - an entire Alaska coastal cruise with interior excursion, no doubt. A shot list of the film can be seen at RailsNorth.com (38:10).
Judging by the subjects, it was filmed by a woman - there are lots of kids and dogs, and no machinery. The amount of snow and the cars that are seen show that it was shot in May-June 1949. The photographer's identity remains a mystery, though, as I bought the film from a woman in Arizona who, in about 1985, acquired it from unknown man in New York.
Our mystery woman begins her travels in Skagway. People along Broadway are seen, and the old suspension bridge across the Skagway River. She then goes on the White Pass & Yukon Route railway to Bennett and Carcross, to Ben-My-Chree on the sternwheeler Tutshi, back on the train to Whitehorse and finally, on the sternwheeler Casca, sails down the Yukon River to Dawson City.
A funny aspect of the film is the editing. It's been spliced so that individual features are shown both northbound and southound consecutively! That makes it difficult to identify places along the Yukon River, as things may or may not be out of chronological order.