By 1902 deep underground mining of gold leads had become the norm with the Great Boulder Mine continuing to discover payable gold 1500 feet below the surface. Later Boulder Mining leases came to be known as "The Golden Mile" and by all accounts this area contained the richest square mile of gold reserves in the world.

Today the Golden Mile continues to be actively worked by Kalgoorlie Consolidated Gold Mines. During the past 20 years the use of modern open cut mining technologies has seen the Golden Mile transform itself into a Super Pit. Current dimensions of the "Super Pit" are 290 metres deep by 1.5 kilometres wide and 4 kilometres long. At current extraction rates KCGM  has proven reserves that should last beyond the year 2013 - by which time the Super Pit will have expanded considerably.