Commentary - the 1982 United Nations Convention the Law of the Sea and the agreement on implementation of part XI - Law of the Sea Convention (p. 78)
US Department of State Dispatch, Feb, 1995
...The United States has 28 maritime boundary situations with its neighbors. To date, 10 of them have been negotiated or adjudicated in whole or in part.
U.S. maritime boundary positions are fully consistent with the rules reflected in the [UN Law of the Sea] Convention. These positions were determined through an interagency process in the late 1970s, prior to the U.S. extension of its maritime jurisdiction to 200 miles.
As a result of that process, the United States determined that equidistance was the appropriate boundary in most cases, but that three situations required a boundary other than the equidistant line: with Canada in the Gulf of Maine/Georges Bank area; with the U.S.S.R. (now the Russian Federation) in the Bering and Chukchi Seas and North Pacific Ocean; and with the Bahamas north of the Straits of Florida. These positions were reflected in the outer limit of the U.S. EEZ, published in the Federal Register (November 4,1976, March 7 and May 12, 1977, and January 11, 1978).
The Senate has given its advice and consent to ratification of boundary treaties related to the following areas: U.S.-Mexico (regarding the territorial sea boundary); U.S. (Puerto Rico and U.S. Virgin Islands)-Venezuela; U.S. (American Samoa)-Cook Islands; U.S. (American Samoa)-New Zealand (Tokelau); and U.S.-U.S.S.R. (now the Russian Federation). The Senate has before it, for its advice and consent, treaties establishing equidistant line boundaries with Cuba and Mexico. The Senate also has before it two recently concluded equidistant line treaties with the United Kingdom in respect of Puerto Rico and the U.S. Virgin Islands, and Anguilla and the British Virgin Islands. (Pending entry into force, the U.S.-Cuba boundary treaty is being applied provisionally pursuant to its terms, extended through biannual exchanges of notes. The U.S.-Mexico boundary is being applied through an interim executive agreement. The U.S.-Russia treaty is being applied provisionally pending ratification by Russia.
With respect to the U.S.-Canada maritime boundary in the Gulf of Maine, most of that boundary was determined through a 1984 award of a Chamber of the International Court of Justice. Regarding the United States and Japan, they have recorded an understanding that recognizes that the respective outer limits of their maritime jurisdiction coincide and constitute a line of delimitation.