Greenland was first explored by Eric the Red, a Norwegian settler in Iceland and father of Leif Eriksson, toward the end of the 10th century, and Icelandic settlements were subsequently established there under his leadership. By the early 15th century, however, these settlements had vanished, and all contact with Greenland was lost. In the course of the search for the Northwest Passage, Greenland was sighted again. The English navigator John Davis visited the island in 1585, and his explorative work, together with that of the English explorers Henry Hudson and William Baffin, afforded knowledge of the west coast of Greenland.

The United States relinquished its claim to land in northern Greenland, based on the explorations of the American explorer Robert Edwin Peary, when it purchased the Virgin Islands from Denmark in 1917. In May 1921, Denmark declared the entire island of Greenland to be Danish territory, causing a dispute with Norway over hunting and fishing rights. In 1931 a strip of land on the east coast was claimed by some Norwegian hunters, whose action was later recognized by the Norwegian government. The occupation was invalidated by the Permanent Court of International Justice at The Hague in 1933.

Germany's occupation of Denmark in 1940, during World War II, brought the status of Greenland again into question. Negotiations between the U.S. government and the Danish minister to Washington resulted in an agreement on April 9, 1941, granting the United States the right “to construct, maintain and operate such landing fields, seaplane facilities and radio and meteorological installations as may be necessary” to protect the status quo in the western hemisphere; the United States also assumed protective custody over Greenland for the duration of World War II, although recognizing Danish sovereignty. Greenland is the source of many of the weather changes in the northern hemisphere, and knowledge of Greenland weather is of prime importance for the prediction of conditions in the North Atlantic Ocean and in western Europe. Weather and radio stations are of inestimable value for Atlantic air traffic. In 1944, during World War II, a German radio-weather station on the northeast coast was destroyed by the U.S. Coast Guard, and various German attempts to establish weather bases on Greenland were thwarted by Coast Guard vessels. In May 1947, Denmark requested that the United States end the 1941 agreement. Protracted negotiations culminated during April 1951, in a 20-year pact providing for Danish control of the chief U.S. naval station in Greenland and for the establishment of jointly operated defense areas. By the terms of other provisions, the armed forces of the members of the North Atlantic Treaty Organization were authorized to use all naval, air, and military bases on the island.