Chris,
I would say that the enormous beak and light mottling on the front make this an immature Bald Eagle. Perhaps it's a female and the one that it was next to was a smaller male?
A Swainson's would be dramatically smaller and less bulky. IMO, size isn't a great differentiator between Balds and Goldens, though they do have somewhat different shapes when perched and definitely when flying.
Peter Ruprecht
Superior