As pop music aged, a need arose for historical indices. Magazines and critics began publishing "all-time" lists. These indices attempted to measure lasting impact, innovation, and cultural resonance. While subjective, they created a shared vocabulary for evaluating pop music as an art form, elevating artists like The Beatles, Bob Dylan, and Aretha Franklin into a pantheon of greatness. These indices were reactive, often correcting or complicating the purely commercial narrative of the charts.