50 CFR § 600.105 - Intercouncil boundaries.
(a) New England and Mid-Atlantic Councils. The boundary begins at the intersection point of Connecticut, Rhode Island, and New York at 41°18′16.249″ N. lat. and 71°54′28.477″ W. long. and proceeds south 37°22′32.75″ East to the point of intersection with the outward boundary of the EEZ as specified in the Magnuson-Stevens Act.
(b) Mid-Atlantic and South Atlantic Councils. The boundary begins at the seaward boundary between the States of Virginia and North Carolina (36°33′01.0″ N. lat), and proceeds due east to the point of intersection with the outward boundary of the EEZ as specified in the Magnuson-Stevens Act.
(c) South Atlantic and Gulf of Mexico Councils. The boundary coincides with the line of demarcation between the Atlantic Ocean and the Gulf of Mexico, which begins at the intersection of the outer boundary of the EEZ, as specified in the Magnuson-Stevens Act, and 83°00′ W. long., proceeds northward along that meridian to 24°35′ N. lat., (near the Dry Tortugas Islands), thence eastward along that parallel, through Rebecca Shoal and the Quicksand Shoal, to the Marquesas Keys, and then through the Florida Keys to the mainland at the eastern end of Florida Bay, the line so running that the narrow waters within the Dry Tortugas Islands, the Marquesas Keys and the Florida Keys, and between the Florida Keys and the mainland, are within the Gulf of Mexico.