"Ain't No Mountain High Enough" is an R&B/soul song written by Nickolas Ashford & Valerie Simpson in 1966 for the Tamla label, a division of Motown. The composition was first successful as a 1967 hit single recorded by Marvin Gaye and Tammi Terrell, becoming a hit again in 1970 when recorded by former Supremes frontwoman Diana Ross. The song became Ross' first solo number-one hit on the Billboard Hot 100 chart and was nominated for a Grammy Award.

The song was written by Ashford and Simpson prior to joining Motown. British soul singer Dusty Springfield wanted to record the song but the duo declined, hoping it would give them access to the Detroit-based label. As Valerie Simpson later recalled, "We played that song for her (Springfield) but wouldn't give it to her, because we wanted to hold that back. We felt like that could be our entry to Motown. Nick called it the 'golden egg'." Dusty recorded a similar verse melody in 'I'm Gonna Leave You' on Dusty.

The original 1967 version of "Ain't No Mountain High Enough" was a top twenty hit. According to record producers, Terrell was a little nervous and intimidated during recording because she did not rehearse the lyrics. Terrell recorded her vocals alone with producers Harvey Fuqua and Johnny Bristol, who added Gaye's vocal at a later date. "Ain't No Mountain" peaked at number nineteen on the Billboard pop charts, and went to number three on the R&B charts.

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