I have searched high and low and I cannot find a Great Lakes polygon shapefile anywhere. All I have found available online are the polyline boundaries of the lakes and they are too complex to be converted to a polygon. I can't seem to download them from the USGS Seamless Viewer. I tried to extract them from the template maps provided in ArcMap but I can't seem to do that, either. Does anyone have any idea where I might find these shapefiles? I appreciate any assistance!