Ballotpedia is an online encyclopedia about American politics and election sponsored by Lucy Burns institute.it is a good starting point for finding out about the elections.
Washington Post live politics blog has updates on the results.
The Conversation has analysis from academic commentators UK and USA
European Parliament think tank issued a briefing prior to the elections on what was at stake for Europe
Chatham House - comment from a UK perspective.
Harvard University has some earlier surveys of political attitudes and engagement especially of young people covering the mid terms and beyond.
Boston University Journalism new service has discussion and updates.