The Helen Mine remained an open pit operation until 1950, from which point on all production came from underground mining. In 1960, the new George W. MacLeod Mine went into production adjacent to the Helen Mine. The ore was transported on an aerial tramline that consisted of over 280 steel three-ton buckets traveling underground and then emerging three-quarters of a mile west of the 2,066-foot vertical MacLeod Shaft. The tramline continued the remaining two miles to the sinter plant on overhead cables. This system was replaced in 1979 by the latest in underground mining technology, the highest-lift single-drive conveyor in the world.