This genre took of so strongly, that it even made it to England, as you can see here. The author's seem to have new methods in their style, but it is great to see what changes have been made and where it is now.
http://www.theguardian.com/books/2009/jan/18/1000-novels-writing-crime-modern-ellroy
http://www.theguardian.com/books/2009/jan/18/1000-novels-writing-crime-modern-ellroy