Ever notice how television (and radio) station call letters all begin with either K or W? In 1923, the Federal Communications Commission decided to separate broadcasters along a common geographic border, to more easily tell where they were coming from. The Mississippi River formed just such a border, and all television stations east of the Mississippi began with W, while those to the west began with K. Of course there weren’t any television stations west of the river at the time, nor would there be for over a decade until KTLA began running in Hollywood, California.

On this day, January 22, in 1947, KTLA channel 5 made its first commercial broadcast. Its max viewership could not have been more than 1,000 – there were not even that many television sets in homes yet. Nevertheless, the premiere broadcast was a star-studded affair, including Hollywood luminaries like Bob Hope and Mickey Rooney.

KTLA made up for its late start by pioneering many of the news broadcast staples we know today: the first continuous live coverage of an event (a boy that fell down a well), and the first helicopter shot. For a long time, KTLA enjoyed a monopoly over its rivals in helicopter news coverage.