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.