Frequently Asked Questions

What is the ECS and how are its limits determined? 

The extended continental shelf, or ECS, refers to that portion of the continental shelf beyond 200 nautical miles from the coast.  ECS limits are determined using the provisions set forth in Article 76 of the 1982 Law of the Sea Convention.  See the About ECS section.

Where is the U.S. ECS and how big is it? 

The United States has ECS in seven regions.  See the U.S. ECS section.

Why delineate the U.S. ECS limits? 

The United States, like other countries, has an inherent interest in knowing, and declaring to others, the extent of its ECS and thus where it is entitled to exercise sovereign rights.  Defining our ECS outer limits in geographical terms provides the specificity and certainty necessary to conserve and manage the resources of the ECS.  The collection and analysis of the data necessary to establish the U.S. ECS limits also enables a better scientific understanding of our continental margins.

Who did the work to determine the U.S. ECS?   

The ECS Task Force, an interagency body of the U.S. Government, coordinated the delineation of the outer limits of the U.S. ECS.  See the About the U.S. ECS Project section.

What data is needed to delineate the U.S. ECS limits? 

Delineating the U.S. ECS limits requires the collection and analysis of bathymetric and seismic data.  See the Data Collection section.

Has the United States made the data it collected for ECS purposes available to the public?  

Yes, data collected as part of the U.S. ECS Project have been made available to the public as quickly as possible after collection and processing.  The data can be downloaded from NOAA’s National Centers for Environmental Information. See the Data Collection section.

What’s down there? 

Much of the ocean – especially the deep ocean – remains unexplored.  Continued mapping and exploration of the ECS will be important to gaining a better understanding of its habitats, ecosystems, biodiversity, and resources.

How many other countries have ECS? 

Approximately 75 countries have delineated their ECS limits. The ECS limits asserted by coastal States can be found on the Commission on the Limits of the Continental Shelf (CLCS) website of the UN Division for Ocean Affairs and the Law of the Sea. See the World Map of ECS areas.

Do any of these countries have overlapping ECS with the United States? 

The U.S. ECS partially overlaps with ECS areas of Canada, The Bahamas, and Japan.  In these areas, the United States and its neighbors will need to establish maritime boundaries in the future.  In other areas, the United States has already established ECS boundaries with its neighbors, including with Cuba, Mexico, and Russia.  With respect to all boundary situations, the outer limits of the U.S. ECS are without prejudice to the question of boundary delimitation with neighboring countries.

What is the Commission on the Limits of the Continental Shelf (CLCS)? 

The CLCS is an expert body established under the 1982 UN Convention on the Law of the Sea (Convention, or Law of the Sea Convention). It consists of 21 members who are experts in geology, geophysics, or hydrography and serve in their personal capacities. The purpose of the CLCS is to review the ECS limits submitted to it by coastal States and make recommendations to those States on the location of their ECS limits.  The CLCS does not, however, approve or grant ECS to coastal States. While the CLCS meets at the UN Headquarters in New York, it is an independent entity created under the Convention. The CLCS’s website is available here.

Will the United States submit its ECS limits to the CLCS? 

The United States has prepared a submission to the CLCS.  The Department of State will file it with the Commission when the United States joins the Law of the Sea Convention.  The United States is also open to filing its submission with the Commission as a non-Party to the Convention.

Are the ECS delineation provisions in Article 76 of the Convention part of customary international law?  

Yes. The longstanding position of the United States is that paragraphs 1 to 7 of Article 76 are part of customary international law. The International Court of Justice has repeatedly concluded that paragraph 1 of Article 76 is part of customary international law. That paragraph provides that the continental shelf extends to “the outer edge of the continental margin or to a distance of 200 nautical miles,” whichever is further. To implement this provision, paragraphs 2 through 7 of Article 76 set forth the detailed rules for determining the precise outer limits of the continental shelf in those areas where the continental margin extends beyond 200 nautical miles.  Like other countries, the United States has used paragraphs 1 through 7 of Article 76 to determine its continental shelf limits and considers these provisions to reflect customary international law. Accordingly, the United States respects the continental shelf limits of other countries that are established in accordance with Article 76.

What is the legal basis for continental shelf rights? 

Customary international law, as reflected in the Convention, confers rights and obligations relating to the continental shelf on all coastal States, including non-Parties to the Convention such as the United States. Article 77 of the Law of the Sea Convention and Article 2 of the 1958 Continental Shelf Convention state that “[t]he rights of the coastal State over the continental shelf do not depend on occupation, effective or notional, or on any express proclamation.”  This provision, along with the International Court of Justice’s 1969 North Sea judgment, reflect longstanding customary international law that provides that continental shelf rights are inherent to the coastal State and derive from a State’s sovereignty over its land territory.   These rights are also exclusive.  Consistent with Article 77 of the Convention, if a coastal State does not explore or exploit the resources of its continental shelf, no one may undertake these activities without its express consent.

Does this Administration support joining the Law of the Sea Convention?  

Like past Administrations, both Republican and Democratic, this Administration supports the United States joining the Law of the Sea Convention.  The announcement of the U.S. ECS limits in no way changes the Administration’s view that the United States should join the Convention.

Joining the Convention would enable the United States to fully protect its navigational rights and freedoms, economic rights, access to critical minerals, and other ocean-related interests.  U.S. accession is also a matter of geostrategic importance.

For decades, the United States has affirmed that the Convention’s provisions concerning traditional uses of the ocean generally reflect customary international law that is binding on all countries, including the United States.  The announcement of the U.S. ECS limits does not change the positions of the United States regarding any provision or article of the Convention.