The 21 Project

In May 2015, Hayes released the project's lead single, "21", exclusively to streaming service Spotify (and later to digital music platforms including iTunes) in an effort to inspire country music to adapt to new, digital forms of music distribution.[5] Over the next two months, he released a series of additional one-off singles that were then incorporated into an extended play, also titled 21, that was released on Spotify on August 7, 2015.[6][7] Hayes told Billboard that "this [current] music wasn't created with an album in mind," but his management team confirmed to the magazine that a conventional physical album was expected to be released in the fall of 2015.[6] Warner Music officially announced said album, The 21 Project, in a press release dated October 12, 2015,[8] and was released on November 6, 2015.[8]

Hayes told country music blog The Boot that due to the way it developed, he's "trying not to call [The 21 Project] a record," but thinks of it more as a box set or an art project.[9] According to him, the goal of the project was to "bring the focus back to the music," and to demonstrate how a song evolves "from its original form into something we play on stage."[2][8] The songs were all rearranged for the acoustic and live performances.[9]

• Justin Eason - bouzouki, acoustic guitar, electric guitar, mandolin, background vocals
• Hunter Hayes - bouzouki, drum programming, acoustic guitar, bass guitar, electric guitar, resonator guitar, mandola, mandolin, percussion, synthesizer, lead vocals, background vocals
• Dave Haywood - mandolin and vocals on "Where It All Begins"
• Charles Kelley - vocals on "Where It All Begins"
• Devin Malone - banjo, cello, acoustic guitar, electric guitar, resonator guitar, slide guitar, background vocals
• Luke Moller - violin
• Hillary Scott - vocals on "Where It All Begins"
• Andy Sheridan - accordion, Fender Rhodes, acoustic guitar, Hammond B-3 organ, keyboards, piano, synthesizer, background vocals, Wurlitzer
• Steve Sinatra - drums, percussion, background vocals
• Matt Utterback - bass guitar, upright bass, synthesizer bass
• Nir Z. - drums

The album debuted at No. 16 on Top Country Albums, and No. 93 on Billboard 200, selling 5,300 copies in its first week.[10] The album has sold 12,400 copies in the United States as of December 2015.[11]