On April 30, 1789, George Washington took the oath of office at Federal Hall in New York as the first president of the United States.

In 1803, the United States completed its purchase of the 828,000 square mile Louisiana Territory from France for 60 million francs, the equivalent of about $15 million. The acquisition roughly doubled the size of the United States.

In 1945, as Soviet troops approached his Berlin bunker, Adolf Hitler took his own life, as did Eva Braun, whom Hitler married the previous day.

In 1975, the Vietnam War ended as the South Vietnamese capital of Saigon fell to Communist forces.

In 1993, the European Organization for Nuclear Research (CERN) announced that the World Wide Web, invented at CERN four years earlier by Tim Berners-Lee, was free for anyone to use, and released its source code to the public domain.