California, Canada and Alaska, During The Alaskan (Klondike) Gold Rush in the late 1890s.
The harsh brutalities of the wilderness are a key element to this story: setting the book next to a pool in Miami might not have had the same effect on Buck’s character.
It's precisely because he suffers the hardship of cold, hunger, and starvation (all brought on by the setting) that Buck transforms as he does, both physically and spiritually. But the hardship of his surroundings also raises the question of why would he choose to freeze his paws off in the woods than snuggle up by some nice man’s fire? Buck’s decision to stay in the wild has more of a powerful effect on us, the reader, since we know it’s not going to be easy living.