I identified the race and some drivers at Road America:

Race 7 (June 24th, 1956)

#16    Bill Lloyd                       Maserati 300 S
#60    Briggs Cunningham      Jaguar Type D
#66    Phil Stewart                   Maserati 300 S 
#111  Carroll Shelby               Ferrari 121 LM  (s/n 0558LM)

(10-21-09)  From author and historian Michael T. Lynch:

"In second pic from the left, top row, Fawcett photos 3, the #60 D Type is not Briggs, but Sherwood Johnston.  Briggs ran #59 in that race."