The Exclusive Economic Zone(EEZ) extends out 200 nautical miles. But if a nation's shelf extends beyond the 200 mile EEZ, that can also be claimed as EEZ.
Obviously, there can be overlapping claims such as between Florida and Cuba in the Florida straits or the Bering Straits between Alaska and Russia.
The US unilaterally established her maritime borders in 1976 with the Magnussen Act. The rest of the world did so in accordance with the UN Convention on the Law of the Seas.
Thks. I’ve been educated.