I'm not sure if anyone is still reading this topic but here are a couple more original backgrounds from the dog race scene and they follow immediately after each other. The first is another multi-layered piece but this time the foreground is painted on paper and all of the gaps are cut out. The buildings in the background are the base layer and the boats, barrels and snow line are foreground. That is how the studio achieved a lot of the "3D" views and were able to animate the dogs etc running behind obstacles. The nice part about this set is that it came complete with a 3 frame hand drawn test cel of Balto running between the boats.. it must have been created early on as you'll notice that it is Balto's original character design.
Here is a close up of some of the detail and join between the two layers
The second background is a panoramic one which allows the camera to sweep across and give a real feel of perspective. As Balto runs out from the boats, he ducks under the timbers before scaling the last boat to jump over the gap in the next frame.
And another close up for some of the detail
Both backgrounds are painted by Ray Rankin and both are quite wide. I had to take about 3 separate photos of each and stitch them together so you can see the completed image. This does take some time and effort and I only do it for fans to enjoy so it is always appreciate should you wish to comment.