Of the four national networks of American radio's classic era, Mutual had for decades the largest number of affiliates but the least certain financial position. For the first eighteen years of its existence, Mutual was owned and operated as a cooperative, setting the network apart from its competitors: Mutual's members shared their own original programming, transmission and promotion expenses, and advertising revenues. From December 30, 1936, when it debuted in the West, the Mutual Broadcasting System had affiliates from coast to coast. Its business structure would change after General Tire assumed majority ownership in 1952 through a series of regional and individual station acquisitions.