What is the harmony for ain't no mountain high enough?

"Ain't No Mountain High Enough" primarily features a rich blend of major chords, creating a soulful and uplifting harmony. The song is built around a progression that includes the tonic (I), subdominant (IV), and dominant (V) chords, often in the key of A major. The use of vocal harmonies, especially in the chorus, enhances the emotional impact, emphasizing the theme of unwavering support and love.