Great Lakes Radiobeacon Maps
There are three maps on this page: 1947, 1965 and 1985,
but they are too large for cellphones.
Here, courtesy of Joe Papworth, K8MP, is a PDF
1947 Great Lakes Beacon Map
which can be enlarged for detailed viewing.
Click on this 1965 map image for a detailed version. From a museum ship display photographed by Tom Drake W4IWH
Click on this 1985 map image for a detailed version.