First it must be admitted that traditional resource and reserve estimates for the United States are somewhat inadequate for calculation of estimates. They are inadequate because they emphasize the shallow and more conventially minable resources rather than the deeper and less accessible resources to which in situ gasification will probably be directed. A further complication is that the original resource estimates occur in many separate reports which often use differing coal thickness, and cover categories as well as different reliability codes. For example, (1) many states do not even report their resources by depth of cover; (2) reported coal thickness categories vary between states; (3) the maximum reported thicknesses are generally cut off at greater than 42 inches for bituminous coals and greater than 10 feet for lignite and subbituminous coals-- such thickness categories do little for delimiting resources of thicker coals; and (4) resource estimates, especially in the Rocky Mountains, are very conservative. This is particularly true in regard to the resources greater than 1,000 feet in depth--depths quite within in situ capabilities.