We report measurements of atmospheric propane (C₃H₈) from analysis of ground-based infra-red solar absorption spectra measured from various sites by the Jet Propulsion Laboratory (JPL) MkIV interferometer. These measurements suggest that exploitation of natural gas fields is a major and growing source of propane in the USA. Also, there seem to be propane sources in large cities such as Los Angeles, possibly related to use of liquefied petroleum gas (LPG).