“Ain’t No Mountain High Enough” marked the first collaboration between soul artists Marvin Gaye and Tammi Terrell in terms of releases. It was the first single from their debut album United where it also appeared as the opening track on the record.

Although they kept their relationship as professional as could be, the two were practically inseparable with most describing them as “brother and sister.” At Terrell’s funeral after her tragic death at the mere age of 24, her mother barred everyone at Motown from attending except Gaye (who also delivered the eulogy) as she felt he was her only friend there. Perhaps there really was no mountain, valley or river that could ever come between them.

The song was listed by writers of the UK publication NME as one of the Top 150 Singles of All Time, and the song was inducted into the Grammy Hall of Fame in 1999. The song would go on to be covered by dozens of artists, including Diana Ross, The Supremes and The Temptations, as well as the songwriters Ashford & Simpson among others.