From the 16th to the 19th century, an estimated 12.5 million enslaved Africans were shipped across the Atlantic to the Americas, with profound consequences for both continents.
The discovery of gold at Sutter's Mill draws some 300,000 people to California from around the world, transforming the American West.
The golden spike is driven at Promontory Summit, Utah, completing the first transcontinental railroad in the United States.
The US-built Panama Canal officially opens, linking the Atlantic and Pacific Oceans.
The New York stock market collapses in late October, heralding the Great Depression that spreads around the world.
Franklin D. Roosevelt becomes president and launches the New Deal programs in response to the Great Depression.
The United States enacts a large-scale economic aid programme to rebuild Western European economies after the Second World War.
Arab oil producers impose an embargo on countries supporting Israel, causing world oil prices to soar.
IBM introduces the IBM PC, whose architecture becomes the de facto standard for personal computers for decades.
The North American Free Trade Agreement between the United States, Canada and Mexico takes effect, creating one of the world's largest trade blocs.
President Bill Clinton announces the lifting of the US trade embargo on Vietnam.
Larry Page and Sergey Brin incorporate Google, which becomes the world's most widely used search engine.