April 30 (UPI) -- On this date in history:
In 1789, George Washington was inaugurated as the first president of the United States.
In 1803, the United States more than doubled its land area with the Louisiana Purchase. It obtained all French territory west of the Mississippi River for $15 million.
In 1812, Louisiana entered the union as the 18th U.S. state.
In 1945, the burned body of Nazi dictator Adolf Hitler was found in a bunker in the ruins of Berlin.
In 1948, 21 countries of the Western Hemisphere formed the Organization of American States.
In 1967, Muhammad Ali was stripped of his world heavyweight boxing championship title after he refused to be drafted into the U.S. military.
In 1975, South Vietnam unconditionally surrendered to North Vietnam. The communists occupied Saigon and renamed it Ho Chi Minh City.
In 1997, Ellen DeGeneres' character came out as gay on the popular sitcom Ellen, making it the first sitcom to feature a gay leading character. The local ABC affiliate in Birmingham, Ala., refused to air the episode so gay rights advocates arranged for a satellite downlink to beam the show.
In 1993, tennis star Monica Seles was stabbed and injured by a self-described fan of Steffi Graf during a break between games in a match against another player in Hamburg, Germany. Seles, who won nine grand-slam singles titles in her career, was out of competitive tennis for more than two years after the attack.
In 2005, the bodies of 113 people, nearly all women and children, were found in a mass grave in southern Iraq.
In 2006, rebel factions in Sudan rejected a peace agreement in the Darfur conflict. Officials estimated the fighting had killed at least 180,000 people and driven more than 2 million from their homes.
In 2012, Israel began construction of a wall that would be 23 feet high and less than a mile long on its border with Lebanon. Security officials said the concrete wall would protect residents in the Matulla area from sniper fire from nearby Lebanese villages.
In 2013, Queen Beatrix, the 75-year-old monarch of the Netherlands, signed a formal declaration abdicating in favor of her eldest son, Willem-Alexander, 46, who became the country's first king in 123 years.
In 2018, Avengers: Infinity War set a U.S. opening weekend box office record with $250 million and $630 million worldwide.