2-1/8" with unusual tin covered back which has center channel holding horizontal brass pin plus stamp of maker W&H. Likely issued for a commemorative celebration  in this famous Black Hills gold rush town established in 1876 and home to such notables as Wild Bill Hickok and Calamity Jane. Shows crowded main street from slight aerial view with four bearded men and a boy in the foreground next to canvas tented structure and a multitude of people in the background all looking towards the photographer. We've seen three. Exc. displaying Mint.