post-apocalyptic sci-fi novel; there was a map showing North America with the coastlines eroded and big grey bubble areas on the continent representing "no-go zones" of radiation

[Lynch]

Would have read this around mid 80's. Don't remember much but I do recall there was a map showing North America with the coastlines eroded and big grey bubble areas on the continent representing "no-go zones" of radiation. Any leads would be greatly appreciated.

[Lobstergirl, au gratin]

Lynch, are you still looking for this or did you find it?