The tar sand resources of the US have the potential to yield as much as 36 billion barrels of oil. The tar sand petroleum extraction technologies now being considered for commercialization in the US include both surface systems and in situ procedures. The surface systems currently receiving the most attention include (1) thermal decomposition processes, (2) suspension methods, and (3) washing techniques. Underground bitumen extraction techniques now being field tested are (1) in situ combustion and (2) in situ steam injection procedures.