Atlantic Cadastral Data

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.

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OPD Images

A standard Official Protraction Diagrams (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 Adobe .pdf files. 

NOTE: Atlantic OPDs that show the Submerged Lands Act and Section 8(g) Zone boundaries do not reflect post-2010 shoreline changes.

SOBD Images

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 contains only current NAD 83 SOBDS. The historic (outdated) SOBDs can be obtained by contacting the Mapping & Boundary Branch. All future activities will be based on the most current SOBDs. 

NOTE: Atlantic SOBDs do not reflect post-2010 shoreline changes.

Image File Formats

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. SOBDs are available as Adobe (.pdf) files that have been compressed with WINZIP.

GIS Files 

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

Note: The precise coordinates of a GIS file can be altered slightly by various GIS functions. For that reason, these GIS files are not an Official Record for BOEM offshore boundaries. Only the coordinates shown on Official OPDs, and SOBDs constitute an Official Record for offshore coordinate values.