a new study from a team of london researchererings is the most comprehensive analysis ever attempted for american pop music. they ran every single that charted on the bill board 100 over the past 50 years to search for a recurring trend. they found that american pop music s evolution has been defined by distinct moments of musical revolution and that america s most influential revolution eclipsed even the 1960s british rock and roll invasion led by bands like the beatles and the rolling stones. according to the researchers the explosion in popularity of hip-hop in 1991 was the single most important event that has shaped the musical structure of the american charts. of course that s probably old news to long-time hip-hop heads but what makes the study unusual is it looked at digital analysis rather than stories and history to uncover the cultural influences of pop music.