Anybody who was old enough to listen to the radio in the early 1970s probably still knows all the words to Don McLean's "American Pie." It was played to death on the radio. Deejays would host 'specials' to analyze the lyrics, trying to parse out all the references to performers or events in McLean's words. (You can still find some of these analyses on line, such as this one, posted on Yahoo! Music in July 2012.)
While some interpretations conflicted, all agreed on this point: "The Day the Music Died" was a reference to the airplane crash on February 3, 1959, outside Clear Lake, Iowa, which killed Buddy Holly and the Big Bopper. A young and not-yet-famous Waylon Jennings was part of Holly's backup band on that tour, and he was supposed to be on that plane, but he gave up his seat at the request of J.P. "The Big Bopper" Richardson, who'd been recovering from the flu and wanted to avoid the bus trip to the tour's next stop in Minnesota.
Just about all the Usual Suspects set aside February 3, therefore, to commemorate The Day the Music Died.
The Iowa crash site was documented in a number of photos by investigators; these are collected at a site called The Day the Music Died: Crash Site Photo Archive. Here's one:
The crash victims had not been removed when these photos were taken.
Today, February 3, is also Four Chaplains Day, remembering the heroic sacrifice of four U.S. Army chaplains, the "Immortal Chaplains," who gave up their life belts and their places in the rescue boats because there weren't enough to go around. The four clergymen were on the USAT Dorchester on February 3, 1943, when the ship was torpedoed by a German U-boat. They were Methodist minister the Reverend George L. Fox, Rabbi Alexander D. Goode, Roman Catholic priest the Reverend John P. Washington, and Reformed Church in America minister the Reverend Clark V. Poling. As the linked Wikipedia article relates, "The chaplains joined arms, said prayers, and sang hymns as they went down with the ship."