Petroleum is a liquid mixture of hydrocarbons that is present in rock strata. The extracted form of petroleum -- crude oil -- is refined into products such as gasoline, diesel, kerosene and asphalt. Colorado oil production dates back to 1860, when the first oil well in the western United States was drilled in Florence, Colorado. 

Colorado continues to be a major oil producer in the U.S. More information on petroleum can be found at the U.S. Energy Information Administration. Colorado has one major refinery, located in Commerce City and operated by Suncor Energy. The refinery produces gasoline, diesel and asphalt. Additional petroleum products are supplied by surrounding states, most heavily from Texas and Wyoming.

Oil and gas development is regulated at the state level by the Colorado Oil and Gas Conservation Commission and the Colorado Department of Public Health and Environment.