Hi Amy,
I’m answering you as a blog entry rather than a comment, so I can include photos. I’ve puzzled over the pictures you sent me of marks on a tree, as well as the details about measurements and known wildlife in your area. I also consulted with an expert woodswoman.
The width of the marks you found is within the range possible for cougars (3.5 to 4.8 inches) or bear (3.75 to 5.5 inches). Cougars would likely only show four claw marks together, as their fifth claw, like a domestic cat, is located separately and further back from the four front claws. Bears can show five claws, but, especially in the case of black bears, the fifth one is usually faint.
However, the real deciding factor was the regularity of the marks (as in the photo to the left). I believe that a wild animal would not make such regular marks (12 sets, separate from each other), and the lines would not be so even and parallel. Also, I think the animal would not scratch upwards, as were the marks shown in one of your photos (shown above).
I’m including a photo of bear marks, which shows that the path of the mark is less regular, and has only four claw marks. The curved lines are more typical of the natural arm movement of a bear. 
The second photo is of cougar marks, and you can see the lines are very thin, and there is a lot of overlap as the cougar scratched repeatedly in the same spot.
So the conclusion I have reached is that the marks on the main tree you found were made by humans. The expert woodswoman I consulted thought some of the marks might have been made using an axe. However, the other marks you found on a different tree were less regular and could have been made by a cougar or bear. Thanks very much for writing and sharing this puzzle with me and the other readers on this blog!