Songfacts®:

• "Thousand Miles" finds Miley Cyrus reflecting on the ups and downs of her relationship with her younger sister Noah and her wanderlust nature.
  
  I told myself I closed that door, but I'm right back here again
  I know half of what I'm saying don't make no sense
  So don't ask me where I been
  
  "I just couldn't imagine not having my little sister in my life," said Miley while discussing this song in her Endless Summer Holiday (Backyard Sessions) special on Disney+.
• Cyrus explained in Backyard Sessions how "Thousand Miles" turned out differently from when she originally penned it. Cyrus wrote it back in 2016 or 2017 when a close friend of hers lost her sister to suicide, and it made her realize how much she loved Noah. So, she wrote the song for her little sister with the title of "Happy Girl."
• During the documentary, Cyrus shared some of the original lyrics.
  
  Verse 1
  
  There was a friend of mine, her name was Darlene but all of us called her Becky
  I don't know why, I knew she was hurting
  But I never thought I'd wake up to that call
  Never at all
  
  Chorus
  
  And I remember on that day I promised you the world
  But soon realized the world ain't what you need
  Now all I want is simply for you to be a happy girl
  Even if that's a world without me
• Cyrus brought in Brandi Carlile to add some yearning harmonies that capture the feeling of regret and the ache of missed opportunities.
• At first glance, "Thousand Miles" sounds like a country ballad - the first couplet includes the phrase "beat-up old Mercedes." But as you keep listening, it becomes a mix of different genres like Americana and synth-pop, with grand piano, harmonica, guitar, and programmed drums all coming together to create something quite unique.
• Cyrus co-wrote "Thousand Miles" with:
  
  Vancouver-based singer-songwriter Tobias Jesso. He is known for his work with Adele, having co-written "When We Were Young" and "To Be Loved." Jesso also co-penned another Endless Summer Vacation track, "Wildcard."
  
  Germany born, Los Angeles-based singer-songwriter Badriia "Bibi" Bourelly. She has co-written several notable songs, including Rihanna's "Bitch Better Have My Money," Demi Lovato's "Anyone" and Nick Brewer's "Talk To Me." Bourelly also co-penned "You" and "Muddy Feet" for Endless Summer Vacation.
  
  Record producer and rapper Mike WiLL Made-It. The Georgia producer first worked with Cyrus in 2013 on her Bangerz album, including its lead single, "We Can't Stop." The two have collaborated on several other projects, including his song "23" featuring Wiz Khalifa and Juicy J, and five tracks on her Miley Cyrus & Her Dead Petz record. He also co-wrote "Violet Chemistry" and "Muddy Feet" for Endless Summer Vacation.
• Mike WiLL Made-It co-produced the track with Kid Harpoon and Tyler Johnson. Harpoon and Johnson are best known for co-writing much of Harry Styles' material. They produced six out of the 12 tracks on Endless Summer Vacation, including the singles "Flowers" and "River."
• The composers played most of the instruments: Tobias Jesso Jr. (keyboards), Tyler Johnson (keyboards, synthesizer, drums, electric piano), Kid Harpoon (bass guitar, synthesizer, drums, guitar, grand piano), Mike Will Made It (drums).
  
  Jamie Arentzen played the harmonica and Emi Trevena the grand piano. Jamie Arentzen is the lead guitarist of the alternative rock band American Hi-Fi and moonlights in Miley Cyrus' touring band.
• During Adele's One Night Only event at Griffith Observatory in LA, Tobias Jesso Jr. crossed paths with Columbia CEO Ron Perry. He expressed interest in involving him in a project with Miley Cyrus. It became clear to Jesso during the session that Ron wanted him to collaborate on writing a piano-based song with Miley. "As soon as all the writers were there - Mike WiLL Made-It, Bibi Bourelly and me and Miley - I was like, 'Why don't we go to the piano and just try some stuff?'" Jesso recalled to Billboard. "I think within 30 minutes, 'Thousand Miles' was written."