This report contains data for 1,127 drainage-area divisions of the Monongahela River Basin, from the headwaters to the confluence of the Monongahela River and Dunkard Creek. Data, compiled in downstream order, are listed for streams with a drainage area of approximately 2 square miles or larger, and for U.S. Geological Survey streamflow-gaging stations. The data presented are the stream name, the geographical limits, the latitude and longitude of the point, the name of the county and the 7 1/2-minute quadrangle in which the site lies, and the drainage area of that site. The total drainage area of the Monongahela River Basin, West Virginia, is 4,374.94 square miles. Figure 2.~Subbasins within the study area. Monongahela River Basin, West Virginia Methods The boundary of the study area was outlined on U.S. Geological Survey (USGS) 7 1/2-minute topographical maps along divides indicated by contour elevations. Drainage-area boundaries were then traced for tributaries with an area of approximately 2 mi2 or larger, which results in 1,127 divisions. These divisions were outlined on 101 USGS 7 1/2-minute topographical maps on file at the Charleston, W. Va., office of the USGS. The areas, stream miles, latitudes, and longitudes of the divisions were determined with an electronic digitizer. The area of each map sheet was measured with the digitizer and compared with the areas of quadrilaterals of the Earth's surface of 7 1/2-minute in latitude and longitude, found in the "InterAgency Coordination of Drainage Area Data" (1951). The areas of the drainage-area divisions were then balanced to agree. Stream miles were measured from the mouth of the stream to the division point and reported to the nearest one-tenth of a mile. The latitude and longitude of each point were reported to the nearest second. Drainage Areas of the Monongahela River Basin The drainage areas for the study area are listed in tabular format for the five major subdivisions of the basin. The name of each stream segment is listed in downstream order. The river mile of each point is the distance measured upstream from the mouth of the stream to the measuring point, with the exception of the Tygart Valley River. The Tygart Valley River is the headwaters of the Monongahela River; therefore, the river miles listed are measured from the mouth of the Monongahela River at Pittsburgh, Pa. The limits of each stream segment are from the previous listed site to a point just upstream from the next listed stream confluence. If the previous site is the drainage-area divide, it is listed as divide. The latitude and longitude of each point is listed by degree (°), minute ('), and second ("). The name of the county and the quadrangle in which the point lies are listed as an aid in locating the segment. The drainage areas are listed according to division, tributary subbasin, and primary subbasin. The area of the division is the drainage area for the stream segment indicated by the limits. The area of the tributary subbasin is the accumulated drainage area of the tributary note...