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This is a list of number-one Mainstream Top 40 hits in the United States by year from the Mainstream Top 40 chart in Billboard Magazine. Chart dates are on a week-ending format.
The Mainstream Top 40 chart (previously called Top 40 Mainstream and being referred to as Pop Songs on Billboard's website since June 2009) tracks "the week's hottest pop songs, ranked by mainstream top 40 radio airplay detections as measured by Nielsen BDS."1