History

The chart debuted in Billboard Magazine in its issued date October 3, 1992, with the introduction of two Top 40 airplay charts, Mainstream and Rhythm-Crossover. Both Top 40 charts measured "actual monitored airplay" from data compiled by Broadcast Data Systems(BDS). The Top 40/Mainstream chart was compiled from airplay on radio stations playing a wide variety of music, while the Top 40/Rhythm-Crossover chart was made up from airplay on stations playing more dance and R&B music.[1]  Both charts were "born of then-new BDS electronic monitoring technology" as a more objective and precise way of measuring airplay on radio stations. This data was also used as the airplay component for Hot 100 tabulations.[1]

Top 40/Mainstream was published in the print edition of Billboard from its debut in October 1992 through May 1995, when both Top 40 charts were moved exclusively to Airplay Monitor, a secondary chart publication by Billboard. They returned to the print edition in the August 2, 2003, issue.[2]