Daniel Boone leads settlers through the Cumberland Gap into Kentucky, opening Shawnee lands to mass white settlement.

The US government forcibly relocates thousands of Cherokee people from their ancestral lands in the devastating Trail of Tears.

The US passes the Guano Islands Act, annexing uninhabited Pacific and Caribbean islands to harvest seabird droppings as fertilizer.

The US defeats Spain in the Spanish-American War and acquires the Philippines, Puerto Rico, and Guam.

The Philippine-American War begins when Filipino independence forces clash with US troops after Spain surrenders the islands to America.

Emilio Aguinaldo is captured by US forces and pledges allegiance to the United States, ending formal Filipino resistance.

Japan simultaneously attacks Pearl Harbor, the Philippines, Guam, and other US territories in a coordinated offensive.

MacArthur withdraws from Manila without defense, leaving the Philippine capital entirely unguarded for Japanese forces to occupy.

The Japanese military forces American and Filipino prisoners to march through brutal conditions in the Bataan Death March.

MacArthur's forces fight a devastating urban battle to retake Manila from Japanese occupation in the most destructive event ever on US soil.

The Philippine flag rises for the first time as the US grants the islands formal independence.

Hawaii and Alaska become US states, dropping the share of people living in the Greater United States from 51% to 2%.

Two Puerto Rican nationalists attempt to assassinate President Truman at Blair House, with one gunman killed by police.

Osama bin Laden coordinates simultaneous bombings of US embassies in Tanzania and Kenya.

Hurricane Maria devastates Puerto Rico's infrastructure, exposing the island's continued status as a neglected American colonial territory.

The United States built its empire through the violent displacement of Indigenous Americans and a decisive victory in the Spanish-American War that delivered the Philippines, Puerto Rico, and Guam. The Philippine-American War tested America's colonial ambitions with a brutal insurgency, while World War II brought the empire's greatest crisis when Japan invaded and occupied its largest territorial possession. After devastating battles, the Philippines was liberated and granted independence, marking a turning point in America's shift from a formal to an informal empire. Hawaii and Alaska became states while Puerto Rican nationalists struck back violently against US authority, illustrating the unresolved tensions of colonial rule. By the late twentieth century, America's informal empire had generated new enemies, most fatally in the form of al-Qaeda, whose attacks demonstrated that empire had simply changed shape rather than disappeared. The story closes with Hurricane Maria's aftermath in Puerto Rico, where the colonial relationship between the mainland and its territories remained starkly unresolved.

The headline events of America's imperial rise and transformation.

White squatters flood Georgia and seize Cherokee land after the state distributes it, defying a Supreme Court ruling in the Cherokee's favor.

Workers on Navassa Island riot and kill five overseers, prompting a Supreme Court ruling that US law applies to guano islands.

Commodore Dewey destroys the entire Spanish fleet at the Battle of Manila Bay, securing American control of Philippine waters.

The Supreme Court's Insular Cases rule that constitutional rights apply only partially in overseas US territories.

Pedro Albizu Campos is assigned to a segregated Black unit during World War I, fueling his turn toward radical Puerto Rican nationalism.

Cornelius Rhoads writes a letter claiming to have killed Puerto Rican patients and calling for the extermination of the island's population.

Filipino villagers from Balangiga attack a US camp, killing 45 soldiers, triggering brutal American reprisals including waterboarding of prisoners.

Japan conquers the Aleutian Islands in Alaska, an invasion the US government censors entirely from public knowledge.

Over 100,000 Japanese Americans are forcibly removed from the Pacific Coast and placed in concentration camps under executive order.

Japanese American soldiers of the 442nd Infantry Regiment become one of the most decorated military units in US history.

The United States successfully manufactures synthetic rubber, eliminating military dependence on colonial rubber plantations in Southeast Asia.

The US forces the 167 inhabitants of Bikini Atoll to permanently vacate their island so it can conduct nuclear weapons tests.

US wartime standardization pressure leads Britain to abandon its own screw thread angle and adopt the American standard instead.

Sony's founders name their brand after an American GI slang term and begin outselling US electronics manufacturers in America's own market.

Chinese workers brought to Saipan produce US-labeled clothing using a legal loophole that bypasses American labor and wage laws.

Behind the headline events of American imperial history lies a series of crucial moments that defined the empire's legal framework and moral character. The Supreme Court's ruling on the Navassa guano island riot established that US jurisdiction could extend beyond the continent, while the later Insular Cases codified a system of limited constitutional rights in overseas territories. The Philippine-American War's darker episodes — from the Balangiga massacre to organized torture — set precedents for American military conduct abroad, and World War II saw Japanese Americans imprisoned at home even as Japanese American soldiers earned extraordinary battlefield honors in Europe. The postwar period brought the twin revelations of nuclear testing displacing the inhabitants of Bikini Atoll and American industrial standardization cementing US technological dominance for decades. Countries that hosted the most American bases, like Japan, rebuilt their industries with US patronage and eventually became fierce economic competitors, exemplified by Sony's rise. The arc closes with Saipan's garment industry exploiting the same legal loopholes that had defined US territorial policy since the nineteenth century.

The overlooked episodes that shaped the empire's character and consequences.

President Roosevelt rewrites his Pearl Harbor address to emphasize Hawaii as American territory while obscuring the scale of losses in the Philippines.

The Louisiana Territory purchase forces US leaders to confront whether a large, racially diverse non-Anglo population can participate in self-government.

Fritz Haber invents a process to synthesize fertilizer from atmospheric nitrogen, ending dependence on guano and later enabling chemical weapons.

The 1900 US presidential election confirms America's imperial policy, crushing Filipino hopes that American voters would demand military withdrawal.

US forces carry out the Bud Dajo massacre, killing every Moro man, woman, and child sheltering in the crater.

Woodrow Wilson blocks racial equality language from entering the League of Nations covenant, disappointing nationalists across the colonized world.

Filipino architect Juan Arellano completes the Manila Legislative Building, publicly rebuking imperialists who doubted Filipino capabilities.

Cornelius Rhoads oversees race-based chemical weapons tests on more than 60,000 soldiers without their full informed consent.

Roosevelt appoints MacArthur commander of all US forces in Asia as Japan's Pacific expansion directly threatens American territories.

Japan offers the Philippines independence and many Filipinos welcome the sight of their own flag flying alone for the first time.

The United States bypasses the Soviet blockade of Berlin by airlifting supplies into the city, demonstrating air power over territorial control.

International aviation officially adopts English as its standard language for all air traffic communications, cementing American cultural dominance in the skies.

Ian Fleming moves to Jamaica and writes James Bond novels that reimagine remote islands as global centers of world-threatening power.

Osama bin Laden forms al-Qaeda in Afghanistan, framing his organization as resistance against American military occupation of Muslim lands.

The US deploys drones to strike individual targets by GPS coordinates across multiple countries, including nominally friendly nations.

The history of the American Empire turns on a series of pivotal decisions and revelations that determined its character and direction across two centuries. From Roosevelt's careful reframing of the Pearl Harbor speech to conceal the Philippines' colonial status, to Wilson's deliberate blocking of racial equality language from the League of Nations, American leaders repeatedly chose to protect the republic's self-image over the rights of colonial subjects. Key scientific discoveries — from Haber's fertilizer synthesis to Rhoads' chemical weapons experiments — show how science and empire intertwined in morally complex ways, while events like the Bud Dajo massacre and Japan's offer of Philippine independence exposed the contradictions at the empire's core. The postwar transformation accelerated as the US leveraged its wartime dominance in logistics, language, and standards into a new kind of informal global power, illustrated by the Berlin Airlift and the adoption of English in international aviation. By the late twentieth century the consequences of this empire had circled back, as figures shaped by proximity to American military bases turned against them, ultimately driving American warfare toward drone strikes that reduced empire to pure coordinates on a map.