Letter Re: Maps of Caves and Mining Districts

Mr. Editor:

I was wondering if you could tell us a resource online where to find the locations of caves/mine shafts, or other underground shelters around the country.  I have tried to do this unsuccessfully, maybe a reader knows?  Thanks. – Robert R.

JWR Replies: That goes a bit outside my expertise. I’m not a spelunker. Perhaps some SurvivalBlog readers have bookmarked some good web sites or could recommend a few books.