the immediate predecessor of mls was the de facto highest level of soccer played in division 2 american professional soccer league that was one of two leagues tracing their genesis to the collapse of the north american soccer league (nasl) in 1984. the nasl formed in 1968 as the merger of the united soccer association and national professional soccer league, both of which had been formed the year before. the nasl, the first league to have u.s. and canadian professional clubs, struggled until the mid-1970s, when its average attendance had grown to 7,770, with four teams averaging over 10,000 in attendance. the 1974 nasl championship game between the los angeles aztecs and the miami toros was televised live on cbs sports, the first national broadcast of a pro soccer match in the united states since 1968. the nasl folded after its 1984 season.