A Final Countdown for Casey Kasem

Casey Kasem has done his final countdown.

The 77-year-old DJ told "American Top 20" listeners across the country Saturday that the program would be his last.

Kasem launched his weekly countdown of the nation's most popular songs, the "American Top 40," on July 4, 1970. Ryan Seacrest took over the show in 2004, and Kasem went on to host two syndicated spinoffs, the "American Top 20" and "American Top 10."

Kasem said he "loved every minute" of his broadcasting career, but that he was leaving the show to "free up time I need to focus on myriad other projects."