3-5/8x6.5" signed envelope for the 1939 centennial of baseball. "1839-1939 Invented By Abner Doubleday Cooperstown, N.Y., June 12, 1939." Envelope features image of ball player standing in front of large baseball bkg. 3¢ stamp features purpletone scene of children playing baseball. "America Prefers Base Balls To Cannon Balls" slogan runs along bottom of envelope. Image of ball player is separated from mailing information by a vertical line where Babe Ruth has signed his name in blue ink. (Ty Cobb, Walter Johnson, Christy Mathewson were also inducted into Hall of Fame in 1936.) Envelope flap has been adhered to inside of envelope. Lt. wear, some aging to area around signature and pinch creases to sides. Signature is distinct and bold. Fine.