Although the United States has virtually unlimited reserves of coal of all ranks, the future availability of domestic coals may be limited by factors which range from the inherent characteristics of the coal itself to the nation's capacity for producing and transporting a high grade product suitable for various end-use markets. In addition to coal's quality characteristics that may restrict its use in certain markets, other limiting factors such as manpower and transportation availability, and inadequate mine production and preparation and cleaning plant capacity are indirectly related to coal supply and availability. Each of these constraints were evaluated in this report and an attempt was made to show their quantitative effect upon the future consumption and use of coal. (Author)