This dataset is a polygon coverage of the resource areas of the Lower Kittanning coal zone. The polygons are subdivided into 2 categories: resource areas inside the outcrop, and areas either too thin, outside the outcrop, or beyond data collection limits. The coal zone must contain at least 14 inches of coal to be a resource. This spatial data set of the Lower Kittanning coal bed and known mined areas is one of many Geographic Information System (GIS) products of the National Coal Assessment that is being conducted by the U.S. Geological Survey in cooperation with State geological surveys and other Federal and State agencies. The Lower Kittanning coal bed is an important economic coal in the northern part of the Appalachian Basin. It is of additional importance because it is one of the coal beds that has potential for coalbed methane development within the Allegheny Group throughout most of the Appalachian foreland basin in Ohio, Pennsylvania, West Virginia, and Maryland. This file is the digital compilation of numerous published and unpublished geologic surveys and depicts the area of occurrence of the Lower Kittanning coal bed and its known mined areas. The coal bed was first mined in southwestern Pennsylvania in the early 19th century but substantial mining did not occur until the advent of the rail lines and canals that were built in the mid-19th century. The Lower Kittanning, which produced nearly 20 million tons of coal in 1996, remains the 7th largest-producing coal bed in the nation and the second largest-producing coal bed in the northern Appalachian region (EIA,1997). The coal is generally low to medium in ash yield and sulfur content, and is a medium- to high-volatile steam and coking coal that is mined by both underground and surface mining methods. The Lower Kittanning coal bed occurs in eastern Ohio, central and northern West Virginia, western Pennsylvania, and western Maryland. Although stratigraphic equivalents to this coal bed may extend into southern West Virginia and eastern Kentucky, correlations are equivocal and do not warrant extrapolation into those areas at this time. The coal bed extent and mined areas will be combined with coal isopach and coal bed structure to calculate original and remaining coal resources. The areal extent of the Lower Kittanning coal zone was digitized from multiple sources using ArcInfo and Arcedit. The digital maps were edited manually in Arcedit and joined to create a single GIS data set (coverage.) See Source_Information and Process_Step for detailed methodology. In West Virginia, much of the area underlain by the coal zone was digitized from reduced transparencies of 1:24,000 scale working maps from the West Virginia Economical and Geologic Survey. The remainder of West Virginia crop was adapted from old topographically-based, 1:62,500 scale county reports from the West Virginia Economical and Geologic Survey. The western and northern extent of the Lower Kittanning coal zone in Ohio was originally scanned from 99 Ohio Geological Survey 1:24,000 scale maps of bedrock geology. Digital files of Ohio crop and surface mines were later combined with digital files of underground mines from the Ohio Department of Environmental Protection. Ohio Geological Survey supplied this combined data set in an Interactive Graphic Design Software file format (.dgn). In Pennsylvania, maps from a variety of sources were digitized. Where available, published or preliminary county reports of reduced 1;24,000 scale maps were digitized. Old topograhically-based, USGS Bulletins were digitized for Lawrence and Beaver Counties. In and around Clearfield County, crop and mines were digitized from Pennsylvania Bureau of Topographic and Geologic Survey Atlas maps at 1:48,000 scale. The remainder of Pennsylvania crop was interpolated or adapted from either topographic maps using Lower Kittanning bore hole data and strip pits or the 1:500,000 scale State geologic map. In Maryland, the crop was digitized or interpolated from 1:24,000 scale USGS coal investigation maps or working USGS maps at 1:24,000 scale.