The NBA originated in 1946 with 11 teams, and through a sequence of team expansions, reductions, and relocations currently consists of 30 teams. The United States is home to 29 teams and one is located in Canada.

The current league organization divides thirty teams into two conferences of three divisions with five teams each. The current divisional alignment was introduced in the 2004–05 season. Reflecting the population distribution of the United States and Canada as a whole, most teams are in the eastern half of the country: thirteen teams are in the Eastern Time Zone, nine in the Central, three in the Mountain, and five in the Pacific.