and Charles Boettcher invested, creating the Colorado Sugar Manufacturing Company in 1899 and contracting E. H. Dyer to build a factory. The failed to succeed, so they sold the plant to local investors, who were able to make it a success. The Campion-Boettcher group then created the Great Western Sugar Company. Retail sales have been important to the economy for decades (e.g., gasoline, and hunting and fishing related sales), and uranium mining-related activities have also been significant. Grand Junction was home to the Climax Uranium Mill, a now decommissioned mill that provided uranium ore to the US Atomic Energy Commission. Education and healthcare have been important to the economy of the area, especially since the 1950s, with the rise of Colorado Mesa University and St. Mary's Hospital as leading employers in these fields. Vast oil shale reserves were known to exist near Parachute, Colorado in the Piceance Basin. The oil embargoes of the 1970s and high gas prices resulted in major financial interest in the region. Exxon purchased rights and used Grand Junction as its seat of operations. The city and the surrounding Grand Valley became prosperous in the 1970s and early 1980s largely because of the effects of oil shale development. The United States, western Colorado in particular, has the largest-known concentration of oil shale in the world (according to the Bureau of Land Management) and holds an estimated 800 gigabarrels of recoverable oil, enough to meet U.S. demand for oil at current levels for 110 years. Known as the "Rock That Burns", the shale can be mined and processed to produce oil. In the past it was significantly more expensive than conventional oil. Sustained prices above $95 per barrel, however, may make extraction economically attractive in the coming years (see Oil shale economics). ExxonMobil pulled out of the region because of lower oil prices, which led to economic hardship in the region. The economic bust, known as "Black Sunday" (May 2, 1982) to the locals, started with a phone call from the president of Exxon to Governor Richard Douglas Lamm, stating that Exxon would cut its losses while retaining mining rights to the (then and currently) uneconomic oil. The economic bust was felt statewide, as Exxon had invested more than 5 billion in the state. Colorado historian Tom Noel observed, "I think that was a definite turning point, and it was a reminder that we were a boom-and-bust