The Old-Time Atlas. It's a comprehensive listing of old-time music events and gatherings happening year-round throughout the United States, arranged by State and by Month, and/or displayed on a map. A brief description of each event is included. The Old-Time Atlas was started in 2013 by two old-time music enthusiasts in East Tennessee.
You can sign up to join their mailing list (for monthly calendar updates), and make use of their Festival Guide for the year of 2013, which includes information on
over 200 old-time music festivals / workshops. You can also submit an event for listing on the Old-Time Atlas using this form.