March 31

The United States and Japan sign the Convention of Kanagawa, opening Japanese ports to American trade after centuries of isolation.

Commodore Matthew Perry and Japanese officials signed the Convention of Kanagawa, opening two Japanese ports to American ships and ending over two centuries of Japan's largely isolationist foreign policy, a pivotal moment that set Japan on a path toward rapid modernization.

The Eiffel Tower officially opens in Paris as the entrance arch to the 1889 World's Fair.

The Eiffel Tower, designed by engineer Gustave Eiffel as the entrance arch for that year's World's Fair, officially opened in Paris after roughly two years of construction. Initially criticized by many artists and intellectuals, it became one of the world's most recognized landmarks.

The United States adopts daylight saving time for the first time, as a wartime measure to conserve fuel.

The United States implemented daylight saving time nationally for the first time, shifting clocks forward to extend evening daylight hours as a wartime energy conservation measure during World War I, a practice later repealed and reinstated multiple times over the following century.

The Motion Picture Production Code, which governed content standards in Hollywood films for decades, is formally adopted.

The Motion Picture Producers and Distributors of America formally adopted the Motion Picture Production Code, a set of moral guidelines restricting depictions of violence, sexuality, and crime in Hollywood films that governed American cinema content for decades until its replacement by the modern rating system.

An earthquake devastates Managua, Nicaragua, killing thousands and destroying much of the capital.

A massive earthquake struck Managua, the capital of Nicaragua, destroying much of the city center and killing an estimated several thousand people, one of the deadliest natural disasters in the country's history and a significant blow to its infrastructure and economy.

The Dalai Lama crosses into India and is granted political asylum after fleeing Tibet.

After an arduous two-week journey through the Himalayas following his flight from Lhasa, the 14th Dalai Lama crossed the border into India, where the Indian government granted him political asylum, allowing him to establish a Tibetan exile community in Dharamshala.

President Lyndon B. Johnson announces he will not seek reelection, amid growing opposition to the Vietnam War.

In a televised address about the Vietnam War, President Lyndon B. Johnson unexpectedly announced he would not seek reelection, a stunning decision reflecting the political toll of the war and growing domestic unrest, reshaping the trajectory of that year's presidential race.

Olympic track legend Jesse Owens, who won four gold medals at the 1936 Berlin Games, dies of lung cancer in Tucson, Arizona.

Jesse Owens, whose four gold medals at the 1936 Berlin Olympics famously undercut Nazi claims of Aryan racial superiority in front of Adolf Hitler, died of lung cancer in Tucson, Arizona, having remained a celebrated symbol of athletic achievement and civil rights progress.

The Warsaw Pact, the Soviet-led military alliance, formally dissolves as Eastern Bloc nations pursue independent paths.

The Warsaw Pact, the Soviet-led military alliance that had bound Eastern Bloc nations together in a counterweight to NATO since 1955, formally dissolved its military command structures as former member states pursued independent foreign policies following the collapse of Soviet-imposed communist governments across the region the previous year. The alliance's full political dissolution followed just months later.

Detroit becomes one of the hardest-hit U.S. cities in the early COVID-19 pandemic, straining its hospital system.

As COVID-19 case counts climbed sharply across the United States, Detroit emerged as one of the hardest-hit American cities in the pandemic's early wave, with hospitals overwhelmed by patients and the virus disproportionately affecting Black residents already burdened by underlying health disparities. The city's struggles highlighted stark racial and economic inequities in health outcomes that drew national attention.