As the World Turns is an American television soap opera that aired on CBS from April 2, 1956 to September 17, 2010. Irna Phillips created As the World Turns as a sister show to her other soap opera The Guiding Light. Running for 54 years, As the World Turns holds the second-longest continuous run of any daytime network soap opera in American history, surpassed only by Guiding Light. As the World Turns was produced in New York City for all of its time. Set in the fictional town of Oakdale, Illinois, the show debuted on April 2, 1956, at 1:30 pm EST. Prior to that date, all serials had been fifteen minutes in length. As the World Turns and The Edge of Night, which premiered on the same day at 4:30 pm EST, were the first two to be thirty minutes in length from their premiere. At first, viewers did not respond to the new half-hour serial, but ratings picked up in its second year, eventually reaching the top spot in the daytime Nielsen ratings by fall 1958. In 1959, the show started a streak of weekly ratings wins that would not be interrupted for over twelve years. The show switched to color on August 21, 1967, and expanded from a half-hour in length to one hour starting on December 1, 1975 when The Edge of Night moved to ABC. In the year-to-date ratings, As the World Turns was the most-watched daytime drama from 1958 until 1978, with ten million viewers tuning in each day. At its height, core actors such as Helen Wagner, Don MacLaughlin, Don Hastings, and Eileen Fulton became nationally known. Three of these actors – Wagner, Hastings, and Fulton – are also the three longest serving actors in the history of American soap operas.