Propane, as compared to other gases over the period of a decade, has fairly consistently been priced above the others when priced per gallon. For instance, in January 2014, propane cost slightly more than kerosene, and three times as much as natural gas, for the same energy output.
Propane is used so widely in heating homes that the supply diminishes quickly and it becomes an issue of prices rising to meet the rise in demand. When demand increases, every single step in the process of getting the propane from the suppliers to a customer costs more, and that makes the gas cost more. Propane also lacks the degree of regulation and subsidies that natural gas has.
Propane costs vary depending on where the gas is being shipped. Homes on the eastern coast of the United States may pay more for propane in a given year than homes in the Midwest, with the conditions of either region playing a part in how different the prices are. It costs more to ship propane to some towns or cities where they would only be able to receive propane shipments by truck. Other cities have lower prices due to more open supply lines, such as trains and pipelines.