The 2000s in rock radio in the United States saw a continued blurring of the playlists among mainstream rock and alternative rock stations. Every track that was ranked by Billboard as the number-one song of the year on its Mainstream Rock Tracks chart during the decade was also a top-five hit on the Alternative Songs chart, most of which topped both charts. In June 2009, Billboard debuted the Rock Songs chart which combined the data of the two charts and its Triple A chart.