News tickers – the scrolling information at the bottom of TV news shows – were first popularized by American news shows wanted to provide emergency safety information on September 11th. The safety information was literally life-saving, but often repetitive. So the newscasters tried used news tickers instead of out-loud reporting. Fox News Channel started a news ticker at 10:49 am Eastern, CNN at 11:11 am Eastern, and MSNBC at approximately 2:00 pm Eastern.
And the big networks decided to keep them ever since, because news tickers allow more streams of information at once (for instance the news caster talking about weather, the ticker providing political updates). Therefore, the news tickers attract a broader audience.
