Event: (Just to butterfly away Reagan's second term and 9/11)
10 PM, February 20, 1981: Argentine Airlines Flight 342 crashes into the North Tower of the World Trade Center during heavy fog. NYFD is unable to extinguish the resulting blaze, and it collapses shortly before midnight. The South Tower is so badly damaged that it also collapses two days later.
The Carter Malaise isn't ending anytime soon, and this will have an effect on popular music: more upbeat tunes to escape the doldrums; more angry and dark ones to emote them.