In 1927, company geologist Donald H. McLaughlin used a winze from the 2,000 level to demonstrate that ore reached the 3,500 foot level. The Ross shaft was started in 1934, a second winze from the level reached , and a third winze from was started in 1937. The Yates shaft was started in 1938. Production ceased during World War II from 1943 until 1945, due to Limitation Order L-208 from the War Production Board. By 1975, mining operations had reached the level, and two winzes were planned to .