The Last Time the U.S. Acquired Territory: How Alaska and Hawaii Became States

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In 1867, the U.S. bought what’s now Alaska from Russia for $7.2 million in gold—roughly two cents an acre. These were the last times the U.S. acquired significant foreign territory and turned it into states. They were also the last times such acquisitions were legally possible.

President Trump asked the Pentagon to draw up invasion plans for Greenland. The ways the U.S. gained land in 1867 and 1898—buying from a weakening empire, military-backed regime change, creative legal workarounds—can’t work anymore. Not because the U.S. lacks the military power, but because the international system that allowed nineteenth-century conquest has been deliberately dismantled and replaced with something different.

How the Alaska Purchase Worked

Secretary of State William Seward saw the northern land as critical to power in the Pacific. Eduard de Stoeckl represented Russia. Seward represented the U.S. They signed the treaty on March 30, 1867.

Seward structured the acquisition as a treaty between sovereign nations, which meant it needed Senate ratification under the Constitution. He needed a two-thirds Senate majority, and he got it, though not without opposition. Critics called it “Seward’s Folly” and “Seward’s Icebox”—a waste of money on frozen wasteland.

What’s missing from this narrative: any consultation with the Tlingit, Haida, Athabascan, and other Native peoples who had lived there for thousands of years. They weren’t asked about Russian rule or being transferred to the U.S. The $7.2 million went to the Russian imperial government. Not a cent reached the indigenous populations whose land was being transferred. This wasn’t an oversight—it was how land acquisition worked in the nineteenth century.

Hawaii: Military Overthrow and Legal Workarounds

Hawaii followed a messier path. The Hawaiian Kingdom was a recognized sovereign nation with diplomatic relations and treaty agreements with the U.S. and other major powers. Businessmen—particularly sugar plantation owners—had established enormous economic interests in the islands by the 1890s, and they viewed Hawaiian sovereignty as an impediment to profit.

Queen Liliuokalani, who took the throne in 1891, tried to strengthen Hawaiian sovereignty and increase Native Hawaiian political power through a new constitution. Businessmen and military personnel, with support from the U.S. diplomatic establishment, overthrew her on January 17, 1893. Naval personnel prevented the Hawaiian monarchy from mounting a military response. A provisional government composed of businessmen replaced the monarchy.

The queen formally protested and maintained she was still the rightful sovereign, but yielded to the military superiority of forces on the islands.

Annexation supporters used a different legal mechanism than the treaty process: a simple majority vote in both houses of Congress—a much lower bar than the two-thirds Senate supermajority required for treaties. The maneuver worked. The Supreme Court later upheld the acquisition, establishing legal precedent for future annexations.

From the Native Hawaiian perspective, this wasn’t a negotiated transfer of sovereignty. It was conquest—a military overthrow of their government followed by unilateral incorporation into a foreign power. The queen never recognized the annexation’s legitimacy. The Native Hawaiian population, the vast majority of Hawaii’s inhabitants at the time, became citizens without consenting to the transformation.

The Long Wait for Statehood

Alaska remained under federal control for ninety-two years before achieving statehood on January 3, 1959. Territorial status meant subordination. Residents elected non-voting representatives to the legislature. They couldn’t vote in presidential elections. They had no senators. Governors were appointed by the president rather than elected locally. The federal government retained ultimate authority over their affairs and could impose legislation without the procedural requirements that applied to states.

For Alaska, the delay reflected practical considerations—sparse population, geographic remoteness, and the sense that full integration seemed impractical. The gold rush in the 1890s brought settlers and economic activity, yet the region remained underpopulated compared to interior states.

Hawaii’s delay was more complicated. The large Native Hawaiian population and recent annexation made some leaders cautious about immediate statehood. Economic interests—particularly sugar plantation owners who had driven the coup—often opposed statehood because they benefited from lower labor and regulatory standards. Full statehood threatened to impose federal protections and wage requirements that would cut into profit margins.

Both places eventually won statehood through local political movements demanding full equality and federal strategic calculations that made incorporation seem advantageous. The decades-long delay revealed how acquisition created a subordinate status that could persist for generations.

The Legal Revolution: 1945 to Present

Between 1898 and 2025 lies a transformation in international law that made nineteenth-century land acquisition obsolete.

The most significant change came in 1945 with the UN Charter. Article 2(4) prohibits member states from using or threatening force against the territorial integrity or political independence of any state. Before the Charter, conquest was understood as an accepted way great powers acquired land. The right of conquest, while controversial, hadn’t been prohibited by international law in the nineteenth century. The Charter changed that foundational principle. Countries gained legal protection for their right to govern themselves. Force couldn’t be used to alter boundaries.

The global decolonization movement reinforced this shift. Dozens of places gained independence from European powers. The principle that people should decide their own government—not have it imposed by outside powers—became embedded in international law. By the mid-twentieth century, self-determination had become a cornerstone of international law with real power to shape geopolitics.

NATO’s Collective Defense Obligation

NATO, established in 1949, introduced an additional constraint that didn’t exist when Alaska and Hawaii were acquired. Article 5 of NATO’s founding treaty says if one member is attacked, each member will take action it deems necessary to assist the attacked party, which may include military force. This mutual defense commitment creates a powerful obligation that applies to all member lands, including Denmark and therefore Greenland.

Denmark’s NATO membership creates a legal wall against military acquisition that didn’t exist in 1867 or 1898, when the places the U.S. sought had no alliance relationships with other great powers. NATO leaders and European officials have explicitly warned that military action would trigger collective defense responses and effectively end the alliance.

Strategic Arguments: Then and Now

Trump’s case for acquiring Greenland echoes nineteenth-century justifications while being divorced from legal reality.

Seward’s strategic argument for the Alaska purchase rested on Pacific security and economic potential. The land would give the U.S. a position for projecting power across the Pacific, enabling military operations and commercial ventures in Asia. There was also a geopolitical security concern: if the U.S. didn’t acquire it, Britain might seize it through Canada, putting a rival power in control of strategically important land.

Hawaii’s strategic case centered on Pacific security and commercial interests. Hawaii’s location made it invaluable as a naval base and coaling station. Military strategists saw it as critical to projecting power and preventing rivals—particularly Japan—from establishing a controlling presence.

Trump’s contemporary case for Greenland follows recognizable patterns. The administration argues that its Arctic location makes it critical to security, pointing to concerns about Russian and Chinese military presence in Arctic waters. Trump has emphasized submarine activity concerns and asserted that control would enhance national security.

None of these arguments, however strategically sound, can justify military conquest in the current context because the legal and institutional framework has fundamentally changed. In 1867 and 1898, a great power could justify acquisition through strategic arguments to its domestic population and the international community. Today, this is no longer the case. Even if Greenland’s strategic value were absolutely unquestionable, the international legal prohibition on conquest would still apply. UN Charter and NATO commitments cannot be suspended based on strategic arguments.

Indigenous Rights: From Dispossession to International Protection

Native populations in Alaska experienced dispossession and systematic disruption following takeover. As settlers and prospectors flooded in after gold discoveries in the 1890s, indigenous populations found themselves increasingly marginalized. Federal policies relegated Alaska Natives to marginal lands and often excluded them from government participation. Laws like the Dawes Act that forced Native Americans to divide up shared tribal lands were extended north with devastating effects on societies structured around collective resource management.

Hunting and fishing rights—central to Native cultures and economies—came under federal restriction. Diseases brought by contact with non-indigenous populations decimated communities. Educational policies aimed at assimilation, often removing children from families to attend boarding schools where indigenous languages and cultural practices were actively suppressed. By the time statehood arrived in 1959, Alaska Natives constituted a small minority, marginalized politically and economically in the land they had originally inhabited.

Native Hawaiians experienced parallel dispossession, with the additional complication of involving the overthrow of a sovereign indigenous government. Following the overthrow and annexation, settlers came to dominate Hawaii demographically, politically, and economically. Native Hawaiians were increasingly excluded from political power and economic opportunity. Land held by Native Hawaiians was appropriated through homesteading, sale by the provisional government, and other legal mechanisms favoring settlers. By the mid-twentieth century, Native Hawaiians had become a minority in their own homeland—a dramatic reversal from their position as the overwhelming majority prior to intervention.

Countries now agree that indigenous peoples have rights to the lands their ancestors lived on, their right to participate in decisions affecting their lands and resources, and their cultural rights to practice traditional languages, religions, and ways of life. The fundamental principle that indigenous peoples possess rights to their lands is now embedded in international law.

Any attempt to acquire Greenland would necessarily implicate the Kalaallit—Greenland’s indigenous Inuit people—whose rights to their land and participation in decisions affecting their homeland are now recognized under international law. Acquisition today would be incompatible with these recognized rights in ways that nineteenth-century acquisition was not—because those rights weren’t yet recognized.

Constitutional and International Legal Constraints

The President cannot take over foreign land or start wars independently. The Constitution gives Congress the power to declare war and reserves treaty-making authority to the President with Senate advice and consent. Any military action to take over another country’s land is an act of war that lawmakers must approve.

Beyond domestic constraints, international law forbids conquest. Article 2(4) of the UN Charter prohibits member states from using or threatening force against the territorial integrity or political independence of any state. The U.S. is a charter member and is legally bound by these commitments. To attack and seize territory by force would be a clear violation, exposing the nation to condemnation by the UN.

More significantly from a practical perspective, attacking a NATO ally would trigger Article 5, creating a collective defense obligation that would unite NATO members in a formal commitment to come to Denmark’s aid. NATO leaders have explicitly warned that such action would trigger collective defense responses and effectively end the alliance.

Why Conquest Is Now Obsolete

The international system has developed mechanisms and norms that make conquest practically impossible for developed democracies. Greenland isn’t available for conquest because it’s the land of a NATO member, because its indigenous population has internationally recognized rights to self-determination, and because any attempt to acquire it by force would violate fundamental principles of international law that the U.S. itself helped establish.

These aren’t merely abstract principles. They’re embedded in institutions and represent the consensus of the international community. Ignoring these rules wouldn’t merely anger allies and break treaties—it would undermine the legal rules that keep the world functioning, a structure that serves U.S. interests in countless other contexts.

The Alaska Purchase and Hawaiian annexation took place in a political and legal environment where conquest by great powers was understood as normal. Countries didn’t yet have legal protection for their right to govern themselves. Indigenous peoples had no recognized rights to their lands or participation in decisions affecting them. Great power security competition was assumed to justify acquisition.

Greenland in 2025 exists in a fundamentally different context. The UN Charter prohibits conquest. NATO guarantees Denmark’s integrity. Its indigenous population has internationally recognized rights to self-determination. Global norms have evolved to make acquisition by developed democracies genuinely obsolete.

This change shows real improvement in how countries treat each other, born from the catastrophic wars of the twentieth century and from sustained struggle by indigenous peoples, colonized places, and principled voices in the international community. The barriers to conquest by developed democracies are real and substantial. Trump’s Greenland threats, however provocative, ultimately highlight not power or the viability of expansion, but rather the degree to which even a president of the world’s most powerful nation cannot override the legal, institutional, and normative frameworks that states have collectively constructed to constrain acquisition.

Those frameworks represent an evolution from the nineteenth-century world when empires expanded through conquest. The ways the U.S. gained land in 1867 and 1898 aren’t politically difficult now—they’re legally impossible, institutionally blocked, and normatively obsolete. That’s not an accident. It’s the result of deliberate choices to build a different kind of world.

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