|River: The Joni Letters is the forty-seventh studio album by Herbie Hancock. The album is a tribute to his long time friend and collaborator Joni Mitchell (whose nineteenth studio Shine, her first since 1998, was released simultaneously) and includes cover of her songs as well as two instrumentals (Duke Ellington's Solitude and Nefertiti by Miles Davis) that influenced her work.
River: The Joni Letters features vocal contributions by Tina Turner, Leonard Cohen, Norah Jones among other as well as Joni Mitchell herself. As a long-time admirer of Mitchell, Prince accepted to play guitar on the cover of Edith And The Kingpin (featuring Tina Turner on vocals). His contribution is uncredited and was unknown until after his passing. The album also contains instrumental covers of Both Sides, Now and A Case Of You (as a bonus track on some edition of the album) that Prince also covered live occasionally or regularly on tours. His own studio version of A Case Of You was released on his 25th album One Nite Alone... in 2002 and on a compilation (A Tribute To Joni Mitchell) released five months before Herbie Hancock's album.
It is not clear where and when Prince contributed his part to Edith And The Kingpin. In 2016, Kat Dyson said that Herbie Hancock and Prince met on 20 March 2005 during the 36th NAACP Image Awards ceremony afterparty thrown by Prince at his rented 3121 Antelo Rd. rented house in Los Angeles, California to discuss this idea. It is likely that the recording took place shortly afterwards. It is not known if Prince's guitar part was recorded before of after Tina Turner's vocals which were recorded at the NJP Studios AG, in Zürich, Switzerland
His contribution to Edith And The Kingpin marks the first known studio track to feature both Hancock and Prince, before Ana Moura's Dream Of Fire released in 2012 (Herbie Hancock had appeared on stage with Prince in 2005, however, as well as on George Clinton's Paisley Park Records album Hey Man... Smell My Finger).
Bonus tracks were added to the digital version on iTunes (Harlem In Havana and I Had A King) and Amazon (A Case Of You and All I Want ) but no single was issued to promote the album.
On 10 February 2008, (Herbie Hancock won the Grammy Award for the Album Of The Year and for the Best Contemporary Jazz Album.
The album met with great success and reached number 5 on the US Billboard 200, and number 1 on the Billboard Jazz Albums Chart.
An expanded edition with the four bonus tracks issued only on digital platforms previously was issued in 2017 to commemorate the tenth anniversary of the album.