1751 - The first volume of Diderot's Encyclopédie was published in Paris.
1838 - Charles Darwin presented a paper on his theory of evolution to the Linnean Society in London.
1847 - The United States Post Office issued its first stamps, a five-cent stamp honoring Benjamin Franklin and a ten-cent stamp for George Washington.
1859 - The first intercollegiate baseball game was played, between Amherst and Williams College.
1862 - The Bureau of Internal Revenue was established by an act of Congress.
1863 - In the Civil War, the Battle of Gettysburg began.
1873 - The province of Prince Edward Island joined the confederation of Canada.
1874 - The first zoo in the United States opened, in Philadelphia, PA.
1898 - In the Spanish-American War, Teddy Roosevelt and his "Rough Riders" waged a victorious assault on San Juan Hill and El Caney in Cuba.
1916 - In World War I, the British launched a massive offensive against German forces in the Somme River region of France.
1934 - The Federal Communications Commission, as mandated in the "Communications Act of 1934", replaced the Federal Radio Commission as the regulator of broadcasting in the United States.
1941 - Mammoth Cave National Park was established in Kentucky.
1943 - "Pay as you go" income-tax withholding started.
1963 - The US Post Office began using the 5-digit ZIP Code system.
1966 - Medicare went into effect.
1968 - The United States, Britain, Soviet Union, and 58 other nations signed the Nuclear Nonproliferation Treaty.
1969 - Britain's Prince Charles was dubbed the Prince of Wales.
1971 - The US Post Office became the US Postal Service.
1979 - The Sony Walkman was introduced.
1980 - 'O Canada' was proclaimed the national anthem of Canada.
1991 - Court TV debuted.
1991 - The Warsaw Pact, the last vestige of the Cold War-era Soviet bloc, was formally disbanded.
1994 - PLO chairman Yasser Arafat drove from Egypt into Gaza, returning to Palestinian land after 27 years in exile.
1997 - Hong Kong reverted to Chinese rule after 156 years as a British colony.
2000 - Vermont's civil unions law, which granted gay couples most of the rights, benefits and responsibilities of marriage, went into effect.
1649 - Gottfried Von Leibniz, German philosopher and mathematician.
1804 - George Sand (Amandine-Aurore Lucille Dupin), French novelist.
1872 - Louis Bleriot, aviation pioneer.
1902 - Myron Cohen, comedian, entertainer, actor.
1908 - Estee Lauder, cosmetics entrepreneur.
1934 - Sydney Pollack, director.
1961 - Lady Diana Spencer, Princess of Wales.