Aaron Copland invented the sound of pop music. In two works from the early 1940s – the Violin Sonata and Appalachian Spring – he introduced a specific, independent harmonic entity which has defined pop music since 1970. This harmonic entity consists of a chord built a fifth above the root. 
 

Aaron Copland: Sonata for Violin and Piano (1943)

 

Aaron Copland: Appalachian Spring – Ballet in one act for full orchestra (1944)

 

Here are just a few of the many famous pop songs that have used this chord…

“So Far Away” (Carole King)

“If You Leave Me Now” (Chicago)

“Josie” (Steely Dan)

“Sailing” (Christopher Cross)

“Love’s Theme” (Barry White)

“One On One” (Hall & Oates)

“Beth” (Kiss)