The largest streetball tournament consisted of 7,296 participants in the Adult Male division of Spokane Hoopfest 2009 in Spokane, Washington, USA from 27-28 June 2009. Hoopfest is an annual 3-on-3 basketball tournament comprised of 26,656 total players on 6,725 teams across 23 different tournament divisions.
Spokane Hoopfest celebrated its 20th anniversay in 2009, organised by the Spokane Hoopfest Association. Regulation-sized basketball half-courts are assembled annually on the streets of downtown Spokane, which closes for the duration of the tournament, to accomodate teams playing 3-on-3 basketball championships. The competition is divided into 449 brackets across 23 competitive categories. According to the organisers' registration documents, 21,364 (80%) of the players were from Washington state, 2,753 from neighboring Idaho, 1,326 from Montana, 630 from Oregon and 583 from other states and Canada.
Comments below may relate to previous holders of this record.