Box lacrosse The roots of indoor lacrosse are obscure, but its invention has been attributed to one Paddy Brennan, a field lacrosse player and referee from Montreal, who, being annoyed by the constant slowing of play from balls going out of bounds in the field game, experimented with indoor games at the Mount Royal Arena during the early 1920s. Joseph Cattarinich and Leo Dandurand, owners of the National Hockey League's Montreal Canadiens in the 1920s, led the participating ice hockey arena owners to introduce the new sport. In the 1930s, 6 v 6 indoor lacrosse came to be played in the summer
Box lacrosse (Senior B national championship) the Founders Cup (Junior B national championship) all under box lacrosse rules. Briefly in 1939, a professional box lacrosse league started up in California, called the "Pacific Coast Lacrosse Association". This four team league also folded shortly after opening. Professional box lacrosse did not return to the United States again until 1968 when the Portland Adanacs and Detroit Olympics franchises played in the National Lacrosse Association, a circuit that folded after one summer season. A new professional indoor lacrosse league was created in the 1970s with the formation of the original National Lacrosse League. This league