NBA history

Professional basketball in the United States spent its early decades in competing leagues before consolidating into the structure recognisable today. The result was a single national competition with a stable franchise model rather than promotion and relegation.

The rules of the game changed the sport more than any single team did. A shot clock forced teams to attack, and the later addition of the three-point line gradually reshaped how space on the floor is used — a change whose full effect took decades to arrive.

Expansion added franchises in new cities and pushed the league to thirty teams, which is the number the current conference and division structure is built around.