Kasem's "American Top 40" began on July 4, 1970, in Los Angeles. The No. 1 song on his list then was "Mama Told Me Not to Come," by Three Dog Night.
The show continued in varying forms - and for varying syndicators - until his retirement in 2009. In his signoff, he would tell viewers: "And don't forget: keep your feet on the ground and keep reaching for the stars."