Geographic Information System (GIS) Data and Maps

The Mapping & Boundary Branch performs mathematical offshore boundary location computations and prepares Official Protraction Diagrams (OPDs), and Supplemental Official OCS Block Diagrams (SOBDs) depicting OCS Block information, the Submerged Lands Act Boundary (aka - State Seaward Boundary), Limit of "8(g) Zone", the Continental Shelf Boundary (CSB) which marks the limit of U.S. jurisdiction for offshore mineral development, and corresponding area measurements. The analytical procedures employed and the computer programs utilized to perform various offshore boundary geometric computations are described in OCS Report MMS 99-0006.

A standard OPD is 1 degree in latitude by 2 degrees in longitude (at lower latitudes: 0 - 48 degrees). At higher latitudes (48 - 75 degrees) such as Alaska and northern Washington, OPDs are 3 degrees wide. OPD limits usually approximate the standard 1:250,000 scale U.S. Geological Survey topographic map series. The OPDs are numbered using the United Nations International Map of the World Numbering System. OPD names usually coincide with standard topographic sheet names when diagrams include land areas. OPD sheet names relate to land features, or to hydrographic features contained within the limits of the diagram. Shoreline planimetric detail is shown when it falls within the limits of a diagram. Older OPDs were prepared on mylar with manual cartographic methods and then scanned into Adobe .pdf files. Newer OPDs were prepared electronically and converted to Arc Info .gra files and Adobe .pdf files

A Supplemental Official OCS Block Diagram (SOBD) is prepared for each block intersected by an offshore boundary (Submerged Lands Act Boundary, Limit of "8(g) Zone", National Marine Sanctuaries, etc.). Note that not all OPDs contain such boundaries, therefore not all OPDs have SOBDs associated with them. The zip files offered here may contain both current and historic NAD 83 SOBDs. The older SOBDs are provided for historical reference, but all future activities will be based on the most current SOBDs

Composite Block Diagrams (CBDs) show NAD 27 lease information portrayed on the NAD 83 cadastre, or show other boundaries that have changed over time. Not all OPDs have CBDs associated with them.

The most current approved revision for each Atlantic Region OPD and SOBD may be viewed and downloaded from the list below. OPDs are offered in Adobe (.pdf) format. OPDs completed after 1996 are also available in Arc/Info Graphics File (.gra) format. SOBDs are available as Adobe (.pdf) files that have been compressed with PKZIP. Adobe (.pdf) files may be viewed with the free Adobe Acrobat reader.

The various boundaries are also offered as ESRI ArcGIS shapefiles. Shapefiles can be viewed with the free Arc Explorer viewer, ArcGIS, or a variety of other GIS systems. The shape files have been zipped using WinZip.

The files below may also be ordered on CD. Contact the Mapping and Boundary Branch.

Atlantic OCS Area Information