jo, using a map won't work, because of the inevitable distortion when the curved earth-surface is depicted on a flat plane of paper.

But you can use the link I noted. Of course, no decent city-name is available for any spot on James Bay, to plug into that link. But the link will accept coordinates of latitude and longitude, which you can get from the map.

On that basis, as I recall, tsuwm is about 740 miles from James Bay.