The Southern California freeways are a vast network of interconnected freeways in the megaregion of Southern California, serving a population of 23 million people. The Master Plan of Metropolitan Los Angeles Freeways was adopted by the Regional Planning Commission in 1947 and construction began in the early 1950s. The plan hit opposition and funding limitations in the 1970s, and by 2004, only some 61% of the original planned network had been completed. The region is well known for its freeways, and they are considered a cultural touchstone. History Origins Southern California's romance with the automobile owes in large part to resentment of the Southern Pacific Railroad's tight control over the region's commerce in the late 19th and early 20th centuries. During his successful campaign for governor in 1910, anti-Southern Pacific candidate Hiram Johnson traveled the state by car, which was no small feat at that time. In the minds of Southlanders, this associated the automobile with clean, progressive government, in stark contrast to the railroads' control over the corrupt governments of the Midwest and Northeast. While the Southern Pacific-owned Pacific Electric Railway's famous Red Car streetcar lines were the axis of urbanization in Los Angeles during its period of spectacular growth in the 1910s and 1920s, they were unprofitable and increasingly unattractive compared to automobiles. As cars became cheaper and began to fill the region's roads in the 1920s, Pacific Electric lost ridership. Traffic congestion soon threatened to choke off the region's development altogether. At the same time, a number of influential urban planners were advocating the construction of a network of what one widely read book dubbed "Magic Motorways", as the backbone of suburban development. These "greenbelt" advocates called for decentralized, automobile-oriented development as a means of remedying both urban overcrowding and declining rates of home ownership. Traffic congestion was of such great concern by the late 1930s in the Los Angeles metropolitan area that the influential Automobile Club of Southern California engineered an elaborate plan to create an elevated freeway-type "Motorway System," a key aspect of which was the dismantling of the streetcar lines, to be replaced with buses that could run on both local streets and on the new express roads. In the late 1930s, when the freeway system was originally planned locally by Los Angeles city planners, they had intended for light rail tracks to have been installed in the center margin of each freeway (which