- The first Christmas cease-fire of World War I began. (1914) This was the first of several unofficial cease-fires in World War I. The truce began when the German soldiers started to decorate their trenches with candles and Christmas trees. The two sides began singing Christmas carols to each other across the "no man's land."
- Henry Ford completed the first useful gas motor. (1893) Though models had been created before, Ford's engine was the first workable gas engine built. Ford built the engine in his spare time while he was working as an engineer at the Edison Illuminating Company. Three years later, Ford developed the "quadricycle," the precursor to the Model T.
- North American Aerospace Defense Command (NORAD) tracked Santa for the first time. (1955) The program began when a misprinted advertisement for a hotline to Santa connected callers to the Continental Air Defense Command Center (CONAD). After getting a call from a little girl asking to speak to Santa, Colonel Harry Shoup instructed staff to give all the callers updates on Santa's location. It became a Christmas tradition, and stayed in place even after CONAD changed into NORAD.
- The "Eggnog Riot" occurred at West Point. (1826) On hearing that their Christmas celebrations had to be alcohol-free, several West Point cadets smuggled in a few jugs of whiskey. Their private party got out of hand, and the entire academy ended up rioting. Shots were fired, and an artillery unit had to be called in to calm things down. Among the participants was future President of the Confederacy Jefferson Davis.
- The Library of Congress caught on fire. (1851) About 35,000 out of the library's 50,000 books were destroyed, including the majority of Thomas Jefferson's private collection. It was later found that faulty chimney flues had caused the library to catch fire.
- Macy's stayed open until midnight for the first time. (1867) The store decided to stay open to an unheard of hour in order to try to catch last-minute shoppers. The strategy paid off, and Macy's made a record $6,000 US Dollar (USD) profit.
- The Ku Klux Klan was founded. (1865) The white supremacist group was formed by Confederate army veterans, including the famous general Nathan Bedford Forrest, the society's first grand wizard. The society was active in working against the policies of the Reconstruction, notably, the enfranchisement of African-Americans.
- Shooting began on the original Star Trek pilot — without William Shatner. (1964) The original pilot actually had none of the classic Star Trek characters except for Mr. Spock. Instead, it featured the adventures of Captain Christopher Pike. NBC executives thought it was too cerebral, and in an unprecedented move, scrapped it and asked for a second pilot. The second pilot, featuring Shatner in his iconic role as Captain Kirk, took off, and is what most people think of as the true beginning of the series.
- Silent Night was sung for the first time. (1818) Father Joseph Mohr had written the lyrics as a poem several years before, but the words were only set to music the day before it was performed. Legend has it that Father Mohr's church organ was broken, and he needed a carol that could be sung to a guitar accompaniment. The song has since been recorded by over 300 artists in more than 40 languages.
- The back-pedal bicycle brake was patented. (1889) Illinois natives Daniel Stover and William Hance were the first to patent a bicycle with a back-pedal brake. Before their invention, bikes used a spoon brake, which was operated by a lever attached to the handlebars.