Closer by The Chainsmokers and Halsey just turned 10 years old this week, and the true story behind the biggest song of 2016 is even wilder than its chart run. It started on a tour bus in 2016, when Drew Taggart wrote a melody in one night with Freddy Kennett of Louis The Child, inspired by Blink-182's I Miss You. The next day, The Chainsmokers' opening act Shaun Frank helped finish the lyrics in a single session and convinced Drew Taggart he could actually sing. But Closer was never supposed to feature Drew Taggart or Halsey at all. Camila Cabello, then a member of Fifth Harmony, recorded the demo of Closer and was set to debut the song live at Coachella with The Chainsmokers. According to Alex Pall, Camila Cabello never showed up, reportedly off hanging out with Taylor Swift, so Drew Taggart performed his verse himself, a guy who had never sung lead on a song in his life, and the Coachella crowd went crazy. Camila Cabello then backed out of Closer completely to focus on Fifth Harmony's album 7/27, leaving The Chainsmokers just weeks to find a new voice. Enter Halsey, who made the second verse of Closer her own story. Closer was released on July 29, 2016, hit No. 1 on the Billboard Hot 100 and stayed there for 12 straight weeks, the longest run of 2016 and at the time one of just 21 songs in Hot 100 history to lead for 11 weeks or more. Then, mid-run, The Fray's Isaac Slade and Joe King were added as co-writers of Closer after comparisons to their 2005 hit Over My Head (Cable Car), meaning The Fray own a piece of the biggest song of 2016 forever. Even a panned debut performance at the 2016 MTV VMAs couldn't slow it down, and Closer eventually went diamond with over 10 million units in the United States. Closer even earned The Chainsmokers and Halsey a Grammy nomination for Best Pop Duo/Group Performance. Closer's reign at No. 1 finally ended in November 2016, on my very first day working at Billboard, dethroned by a song I'm asking you to name in the comments. So here is the real question a decade later: did Camila Cabello make the worst decision in modern pop history by passing on Closer, or did Camila Cabello, Halsey and The Chainsmokers all end up winning? #chainsmokers #closer #halsey #camilacabello #thechainsmokers - @kevankenney