New categories

I've now started to add some new categories to the site, providing links to pages/sources on the civil war, slavery, and the growing sectional tensions of the 19th century. These will added to in the usual ad hoc way. As for the rest of the site, recent links include some useful videos and further attempts to build the 80s & 90s links, still a bit thin, so do pass on any suggestions. As ever, please link and share the site as much as you can.