The American Youth Soccer Organization (AYSO) is a major non-profit youth soccer league in the US for children aged 4-19, founded in 1964 at Jefferson Elementary School in Torrance, California, with just nine teams. Today, it has grown to over 50,000 teams and 630,000 participants, operating through local "Regions" across all 50 states, the U.S. Virgin Islands, and Trinidad and Tobago, and is largely run by volunteers. The organization is structured into regions, areas, and 14 sections, overseen by a national board of directors, and offers extensive training programs for volunteer coaches and referees, emphasizing "Positive Coaching" and certified officiating. Its alumni include some of the biggest names in American soccer, such as Landon Donovan, Alex Morgan, Julie Foudy, and Carlos Bocanegra. Headquartered in Torrance, California, AYSO remains a cornerstone of youth sports development in the United States.