​1933 -1940: H. B. Northrup Mining Company's Gary Underground Mine in Hanna, Wyoming

Notes by Bob Leathers

The H. B. Northrup Mining Company's Gary underground coal mine opened for production of coal in 1933 and abandoned in 1940. H. B. Northrup operated the Gary mine for 4 years. During that time, the mine produced 7,017 tons of coal with a peak work force of 6 workers in 1933. The mine experienced no fatalities.