The Answer:

The American network television show with the longest continuous run is Meet the Press, which has been airing weekly on NBC since November 6, 1947. (It began as a radio show two years prior to that.)

As measured by number of episodes aired, we believe that honor goes to the CBS Evening News, which has been running nightly since August 15, 1948. It started as a 15-minute show, and expanded to a half hour in 1963.

Finally, as measured by hours of television aired, the winner is easily The Today Show, which has aired weekday mornings on NBC starting January 14, 1952. It began as a two-hour show in any given time zone (though the hosts broadcast multiple editions live until 1958, when they began using tape-delay instead). Since 2000, it has aired three hours a day.

—The Fact Monster