Science Fair Project Encyclopedia Billboard is a weekly American
magazine devoted to the music industry. It maintains several
internationally recognized music charts that track the most
popular songs or albums in various categories on a weekly basis.
Its most famous chart, the "Hot 100" survey, ranks the top 100
songs regardless of genre and is frequently used as the standard
measure for ranking songs in the United States. The "Billboard
200" survey is the corresponding chart for album sales. When
founded in 1894, Billboard magazine was originally concerned
with carnival entertainment, but music coverage grew to the
point that its earlier subjects were spun off into a separate
journal in the 1950s. On January 4, 1936 Billboard magazine
published its first music hit parade and on July 20, 1940 the
first Music Popularity Chart was calculated. Since 1958 the Hot
100 has been published, combining single sales and radio airplay
. Radio countdown programs For many years, the weekly syndicated
radio program "America