It was the first outdoor soccer league to feature teams from throughout the United States since the demise of the original North American Soccer League in 1984. Between 1990 and 1995 it was the de facto top professional soccer league in the United States. After 1993 it was also the top league in the Canadian soccer pyramid.
However it was never officially granted Level 1 / Division 1 status on the United States soccer pyramid because, at the time, FIFA would not give this status to leagues that crossed national borders. In 1993, it applied for the vacant Level 1/Division 1 role but lost out to Major League Soccer.
For its final two seasons, 1995 and 1996, the APSL changed its name to the "A-League". It was subsequently absorbed by the emerging United Soccer Leagues organization. The USL retained the A-League name until 2004 when it became the USL First Division.
In 1989, Fort Lauderdale Strikers, the winners of the American Soccer League defeated San Diego Nomads, the winners of the Western Soccer League in a play-off game and as a result were declared United States soccer champions. In 1990, the two leagues merged as the American Professional Soccer League. However, during its inaugural season, in order to avoid high travel expenses, the APSL remained essentially two separate leagues. The ASL became the American Soccer Conference and featured teams from the East Coast, while the WSL became the Western Soccer Conference and featured teams from the West Coast. Teams only played other teams from within the same conference and it was not until the title decider, between Maryland Bays and San Francisco Bay Blackhawks that teams from the two different conferences actually met in a competitive game.
Throughout its existence, the league would struggle financially and its roster of teams quickly dropped from 22 in 1990 to just 5 in 1992. However, in 1993 the league received a lifeline when following the demise of the Canadian Soccer League, three former CSL clubs – Vancouver 86ers, Montreal Impact and Toronto Blizzard – joined the APSL.