"Bandstand" premiered on October 13, 1952 in Philadelphia, and then began airing on the network on August 5, 1957 from 3:00 to 4:30 Eastern time, with an additional half hour that was seen in Philadelphia only.
Johnny Carson's "Who Do You Trust?" moved from 4:30 to 3:30 as of November 18, 1957, thus cutting "American Bandstand" into two separate segments, except in Philadelphia. This lasted for 10 months, until ABC moved "American Bandstand" to 4:00.
On October 2, 1961, the show was shortened from 90 minutes to 50 minutes, with the remainder of the full hour taken up by an ABC news program intended for teenagers called "American Newsstand."
When "American Bandstand" made the move to Saturday afternoons as of September 7, 1963, it got back its full hour. Hobbled by preemptions for college football throughout the 1980s, it spent its last network season as only a half hour long; it last aired on ABC on September 5, 1987.
It then went into syndication as an hour long show for two years. In its last gasp, it ran on USA Network from April to October of 1989 with a new host, David Hirsch.