In Chapter 1, the final destination of the train is Seattle.
To determine this fact, we trace Buck's journey from the moment Manuel sells the St. Bernard and Scottish Shepherd cross-breed to a stranger. Buck starts his journey at the train station in California. The stranger takes him by train to San Francisco. Caged up in a crate, Buck is then shipped by truck, ferry steamer, and finally by train all the way to Seattle. This is the train's last stop. During the journey to Seattle, Buck is not fed or given any water for two days and two nights.
In Seattle, four men carry Buck's crate off the train; this is where the stout man in the red sweater makes an appearance. He starts to pry the crate open with a hatchet. When the crate is finally open, Buck rushes out with great fury. However, the man in the red sweater is poised for an attack and brandishes his club readily. He beats Buck senseless with the club; this moment is Buck's first initiation into the Law of the Club.
The man in the red sweater eventually sells Buck for three hundred dollars to two French Canadian government couriers, Perrault and Francois.