In hindsight, it seems like a simple decision. But it changed the industry and TV news as we know it. 

On  Sept. 2nd, Labour Day weekend, in 1963, CBS became the first TV network in history to do an actual half hour newscast. Before that time, all TV news was restricted to 15 minutes, usually around 6 PM. No one knew if the audience would sit through 30 minutes of news. 

We now know it as the norm. But at the time, the network took a chance and elevated Walter Cronkite to almost mythical status.

"Fifteen minutes was the industry standard, a format that left little room for context, field reports, or interviews that ran more than a few sentences. CBS had aired a national evening news program since 1948, first under Douglas Edwards and then, beginning in April 1962, under Cronkite.

The expansion was a bet that viewers would stay for more than headlines and that affiliates would surrender extra commercial time in the early evening. NBC followed with its own half-hour newscast a week later. ABC did not match the format until 1967..."

No one back then could even have considered an all news network like CNN. But it might not exist if the networks hadn't proved there's an audience for news. 

63 Years Ago: CBS Aired The First Regular 30-Minute Evening News – A Look Back At CBS News