While several countries have made claims to parts of Antarctica, most of Marie Byrd Land (the portion east of 150°W) has not been claimed by any sovereign nation. Signatories to the Antarctic Treaty of 1959 agreed not to make such claims, except the Soviet Union and the United States, who reserved the right to make a claim.
The Norwegian claim to Queen Maud Land left its southern boundary undefined,[39] so the southern part of that segment of Antarctica may also have been unclaimed. Norway resolved that ambuguity on 12 June 2015 when it formally annexed that area.[40]