On December 18, 1915, President Woodrow Wilson marries Edith Galt in Washington, D.C. The bride was 43 and the groom was 59. It was the second marriage for Wilson, whose first wife died the year before from a kidney ailment. Edith, who claimed to be directly descended from Pocahantas, was the wealthy widow of a jewelry-store owner and a member of Washington high society.

On December 18, 1932, the Chicago Bears defeat the Portsmouth (Ohio) Spartans, 9-0, in the NFL's first playoff game—and first game played indoors. The victory gives the Bears the championship and leads to a playoff system for the first time. Because of frigid weather and waist-deep snow, the game was moved from Wrigley Field to Chicago Stadium, home of the city's NHL team.

Just weeks after being elected the junior senator from Delaware, Joe Biden’s first wife, Neilia, and 13-month-old daughter, Naomi, are killed in a car accident while out shopping for a Christmas tree on December 18, 1972, when a tractor-trailer strikes their vehicle.

On December 18, 2019, after weeks of discussions among legislators, the House of Representatives vote to impeach the 45th President, Donald Trump, for abuse of power and obstruction of Congress. The vote fell largely along party lines: 230 in favor, 197 against and 1 present. Trump became only the third president ever to be impeached, joining Andrew Johnson and Bill Clinton, after concerns about his alleged attempts to seek foreign interference in the 2020 election.