The Call of the Wild (movie, 1972)

John Thornton, is a fearless man who's after more than gold; he wants to do what's right. Thornton works for the U.S. mail and is the only person daring and smart enough to figure out how to travel the deadly 600 miles from Skagway to Dawson, Alaska in the icy winter. His incredibly dog Buck is by his side and part of how he survives.