Statement of responsibility: [Works Progress Administration of Pennsylvania]. Relief on most maps shown by contours and spot heights. WPA Project Numbers: 4483 -- 19666 -- 25734 -- No. 65-23-5001 -- No. 465-23-3-192. Each sheet is named and may have a letter code of A, B, C, or D following the name, corresponding to specific government contracts. These letter codes indicate a particular contract as follows: A = Contract No. 4483; B = Contract No. 65-23-5001 + No. 465-23-3-192; C = Contract No. 19666; and D = Contract No. 25734. Contract 19666 was used for mapping the oil and gas wells involved. Maps cover the time period of 1934-1936, project was intended to continue through 1938. There are ca. 1159 possible sheets. The set includes some base maps without any mine information on them. Some maps, including some base maps, show oil and gas wells and whether they are active or abandoned, in addition to coal seams. Some coal seams are mis-identified, some mines are omitted, and some mine locations are mis-mapped. Some sheets include handprinted notes indicating the source of contours used, whether from actual survey or from an existing base map, for that particular sheet. Sheet numbering is based on a system of subdividing a 15-minute quadrangle base map into 9 equivalent 2.5-minute segments; in some cases not all nine segments were used as part of the mapping done for the project. Sponsored by the Pennsylvania Bureau of Mines. Includes multiple sheets of some quadrangles to display different coal seams and/or oil and gas wells within the same region. Shaded, dotted areas represent retreat mined areas. Specific coal seams are abbreviated as follows: Brookville = Brk. -- Clarion = Clar. -- Lower Bakerstown = LB -- Lower Freeport = LF -- Lower Kittanning = LK -- Middle Kittanning = MK -- Pittsburgh = Pitt. -- Sewickley = Sew. -- Upper Freeport = UF -- Upper Kittanning = UK -- Washington = Wash. -- Waynesburg = Wayn. -- Redstone = Red. Some maps include structural contours. Some sheets/seams were mapped multiple times ...