Original 1st printing, 14x20 &1/8" concert poster for The Steve Miller Band, Muddy Waters, and the A.B. Skhy Blues Band at the Avalon Ballroom in San Francisco, Ca, on 9/20-22/1968.  
 
Image is #138 the Family Dog/Avalon series. 
 
Art by Wes Wilson.
 
The poster is in vintage condition. There is significant toning on the front, tackholes throughout, and some light surfacewear.