The NBA has held its annual playoffs every year since its inception as
the Basketball Association of America in 1946. The first playoffs were
held in 1947, when only six teams qualified for the postseason. The
bracket was different from the format that would eventually become
standard in professional basketball.
The top team from the Eastern Division and the top team from the Western
Division received first-round byes and then played each other in the
second round. The second- and third-place teams from each division played
in the opening round.
Both Eastern Division teams advanced through the lower-seeded side of the
bracket and eventually faced each other. In the first BAA Finals, the
Philadelphia Warriors defeated the Chicago Stags four games to one to win
the league's first championship.
Following the merger with the National Basketball League, the postseason
developed into a more familiar bracket. The top teams in each division
were matched against lower-seeded teams, with the winners advancing until
the Eastern and Western champions met for the NBA championship.
From 1947 through 1949, the early rounds used shorter best-of-three
series, while portions of the bracket and the BAA Finals used longer
series. When the league expanded its playoff field to eight teams in
1949, the first two rounds were best-of-three series and the Finals
remained best-of-seven. The second round was later expanded to a
best-of-five format.
The number of NBA teams declined during the 1950s, and by 1955 the
playoffs again included six teams, with the top team in each division
receiving a bye. The postseason eventually returned to eight teams and
continued expanding as the NBA added franchises.
The field grew to 10 playoff teams in the 1970s and later to 12. By the
1980s, the NBA had adopted the 16-team tournament-style playoff field
that became the basis of the modern postseason.
From the 1980s through 2003, the opening round was played as a shorter
best-of-five series. Beginning in 2003, every traditional playoff round
became a best-of-seven series.
