The Basketball Association of America was founded in 1946 by the owners of the major ice hockey arenas in the Northeast and Midwest United States. On November 1, 1946, in Toronto, Canada, the Toronto Huskies hosted the New York Knickerbockers which the NBA now regards as the first game played in the league's history. Although there had been earlier attempts at professional basketball leagues, including the American Basketball League and the National Basketball League, the BAA was the first league to attempt to play primarily in large arenas in major cities. During its early years, the quality of play in the BAA was not significantly better than in competing leagues or among leading independent clubs such as the Harlem Globetrotters. For instance the 1948 ABL finalist Baltimore Bullets moved to the BAA and won its 1948 title, followed by the 1948 NBL champion Minneapolis Lakers who won the 1949 BAA title.

On August 3, 1949, the BAA agreed to merge with the NBL, expanding the National Basketball Association to seventeen franchises located in a mix of large and small cities, as well as large arenas and smaller gymnasiums and armories. In 1950, the NBA consolidated to eleven franchises, a process that continued until 1954, when the league reached its smallest size of eight franchises, all of which are still in the league (the Knicks, Celtics, Warriors, Lakers, Royals/Kings, Pistons, Hawks, and Nationals/76ers).

While contracting, the league also saw its smaller city franchises move to larger cities. The Hawks shifted from "Tri-Cities" (the area now known as the Quad Cities) to Milwaukee (in 1951) and then to St. Louis (in 1955); the Royals from Rochester to Cincinnati (in 1957); and the Pistons from Fort Wayne to Detroit (in 1957). In 1960, the Lakers relocated to Los Angeles, California, and the Warriors moved to San Francisco, California, in 1963. The following year, the Nationals left upstate New York to bring basketball back to Philadelphia, changing their nickname from "Nationals" to "76ers." This means out of the original eight franchises, only the Knicks and Celtics have not relocated at any point.

Although Japanese-American Wataru Misaka technically broke the NBA color barrier in the 1947-48 season when he played for the New York Knicks, 1950 is recognized as the year the NBA integrated with the addition of African American players by several teams including Chuck Cooper with the Boston Celtics, Nat "Sweetwater" Clifton with the New York Knicks, and Earl Lloyd with the Washington Capitols. Today, more than fifty years later, the NBA is made up of players of many different races, with diverse backgrounds and cultures. Over 80% of NBA players today are African American.

During this period, the Minneapolis Lakers, led by center George Mikan, won five NBA Championships and established themselves as the league's first dynasty. To encourage shooting and discourage stalling, the league introduced the 24-second shot clock in 1954. If a team does not attempt to score a field goal (or the ball doesn't make contact with the rim) within 24 seconds of obtaining the ball, play is stopped and the ball given to its opponent.

In 1957, rookie center Bill Russell joined the Boston Celtics, who already featured guard Bob Cousy and coach Red Auerbach, and went on to lead the club to eleven NBA titles in thirteen seasons. Center Wilt Chamberlain entered the league in 1959 and became the dominant individual star of the 1960s, setting new records in scoring and rebounding. Russell's rivalry with Chamberlain became one of the great individual rivalries in the history of American team sports.

Through this period, the NBA continued to strengthen with the shift of the Minneapolis Lakers to Los Angeles, the Philadelphia Warriors to San Francisco, and the Syracuse Nationals to Philadelphia, as well as the addition of its first expansion franchises. The Chicago Packers (now Washington Wizards) became the 9th NBA team in 1961. From 1966 to 1968, the league expanded from nine teams to fourteen, introducing the Chicago Bulls, Seattle Supersonics, San Diego Rockets (who relocated to Houston four years later), Milwaukee Bucks, and Phoenix Suns. Then in the 1970s, it was extended to seventeen teams as the Portland Trail Blazers, Cleveland Cavaliers, and Buffalo Braves (now the Los Angeles Clippers) all made their debuts.

In 1967, the league faced a new external threat with the formation of the American Basketball Association. The leagues engaged in a bidding war. The NBA landed the most important college star of the era, Kareem Abdul-Jabbar (then known as Lew Alcindor), who together with Oscar Robertson led the Milwaukee Bucks to a title in his second season, and who later played on five Laker championship teams.

However, the NBA's leading scorer, Rick Barry jumped to the ABA, as did four veteran referees�Norm Drucker, Earl Strom, John Vanak, and Joe Gushue.

The American Basketball Association also succeeded in signing a number of major stars, including Julius Erving, in part because it allowed teams to sign college undergraduates. The NBA expanded rapidly during this period, one purpose being to tie up the most viable cities. From 1966 to 1974, the NBA grew from nine franchises to 18; the New Orleans Jazz (now in Utah) came aboard in 1974. Then, following the 1976 season, the leagues reached a settlement that provided for the addition of four ABA franchises to the NBA, raising the number of franchises in the league at that time to 22. The franchises were the San Antonio Spurs, Denver Nuggets, Indiana Pacers and New York Nets. Some of the biggest stars of this era were Kareem Abdul-Jabbar, Rick Barry, Dave Cowens, Julius Erving, Walt Frazier, Artis Gilmore, George Gervin, Dan Issel and Pete Maravich.

The league added the ABA's innovative three-point field goal beginning in 1979 to open up the game. That same year, rookies Larry Bird and Magic Johnson joined the Boston Celtics and Los Angeles Lakers respectively, initiating a period of significant growth in fan interest in the NBA throughout the country and the world. Bird went on to lead the Celtics to three titles, and Johnson went on to lead the Lakers to five. Also in the early '80s, the NBA added one more expansion franchise, the Dallas Mavericks, bringing the total to 23 teams.

Michael Jordan entered the league in 1984 with the Chicago Bulls, providing an even more popular star to support growing interest in the league. This resulted in more cities demanding teams of their own. In 1988 and 1989, four cities got their wishes as the Charlotte Hornets, Miami Heat, Orlando Magic, and Minnesota Timberwolves made their NBA debuts. Globalization also occurred in the 1980s. A growing number of NBA star players also began coming from other countries. Initially, many of these players, such as 1994 NBA MVP Hakeem Olajuwon of Nigeria, first played NCAA basketball to enhance their skills

Jordan along with Scottie Pippin would lead the Bulls to six championships in eight years during the 1990s. Olajuwon won back-to-back titles with the Houston Rockets in '94 and '95.

The 1992 Olympic basketball Dream Team, the first to use current NBA stars, featured Michael Jordan, Larry Bird, and Magic Johnson. In 1995, the NBA expanded to Canada and to 29 teams with the Toronto Raptors and the Vancouver Grizzlies. In 2001, the Vancouver Grizzlies were relocated to Memphis, which left the Toronto Raptors as the only Canadian team in the NBA.

In 1996, the NBA created a women's league, the Women's National Basketball Association (WNBA). In 1998, the NBA owners began a lockout which lasted 191 days and was settled on January 18, 1999. As a result of this lockout the 1998-99 NBA season was reduced from 82 to 50 games (60%), which were all played in 1999 only, thus calling it the 1999 NBA season. San Antonio won the championship on June 25th by beating the New York Knicks.

In 2004, two years after the Hornets relocation to New Orleans, the NBA returned to North Carolina as the Charlotte Bobcats were formed.

Since the break-up of the Chicago Bulls in the summer of 1998, the Western Conference has dominated the NBA, winning 7 of 9 championships. Tim Duncan and David Robinson won a championship in 1999 with the San Antonio Spurs, and Shaquille O'Neal and Kobe Bryant started the 2000s off with the three straight championships with the Los Angeles Lakers. The Spurs won in again 2003 against the Nets, with the Lakers returning to the Finals in the following year, only to fall to the Detroit Pistons (the only championship team since 1998 that didn't have either Tim Duncan or Shaquille O'Neal). In the off-season, O'Neal was traded to the Miami Heat, and the Lakers and Bryant did not win another playoff series until 2008. San Antonio won their third championship in 2005 with a nucleus of Tony Parker, Manu Ginobili, and Duncan. In 2006, O'Neal won title number four with the Miami Heat, giving the franchise its first championship. San Antonio then swept LeBron James and the Cleveland Cavaliers in 2007, giving them title four titles in nine years. Between them, O'Neal and Duncan have been to each of the last nine NBA Finals and have won eight out of nine titles. Together, they have won six Finals MVP awards and three league MVPs.

In some occasions, young players from the English-speaking world tend to attend U.S. colleges before playing in the NBA (notable examples are Canadian Steve Nash, 2005 and 2006 MVP, and Australian Andrew Bogut, the top draft pick in 2005), while other international players generally come to the NBA from professional club teams. Currently, the Toronto Raptors have the most international players in the NBA. The NBA is now televised in 212 nations in 42 languages.

In 2001, an affiliated minor league, the National Basketball Development League, now called the NBA Development League (or D-League) was created.

On June 29, 2006, a new official game ball was introduced for the 2006-07 season, marking the first change to the ball in over 35 years and only the second in 60 seasons. Manufactured by Spalding, the new ball featured a new design and new synthetic material that Spalding claimed offered a better grip, feel, and consistency than the original ball. However, many players were vocal in their disdain for the new ball, saying that it was too sticky when dry, and too slippery when wet.

On December 11, 2006, Commissioner Stern announced that beginning January 1, 2007, the NBA would return to the traditional leather basketball in use prior to the 2006-2007 season. The change was influenced by frequent player complaints and confirmed hand injuries (cuts) caused by the microfiber ball.[4] The Players' Association had filed a suit in behalf of the players against the NBA over the new ball.[5] As of 2006, the NBA team jerseys are manufactured by Adidas, which purchased the previous supplier, Reebok.

On July 19, 2007, the FBI investigated allegations that veteran NBA referee Tim Donaghy bet on basketball games he officiated over the past two seasons and that he made calls affecting the point spread in those games.[6] On August 15, 2007, Donaghy pleaded guilty to two federal charges related to the investigation. However, he could face more charges if it is determined that he deliberately miscalled individual games.

On February 19, 2008, the NBA declared that the Phoenix Suns and the Denver Nuggets will play the first outdoor game on October 11, 2008, at the Indian Wells Tennis Garden. It will be the first outdoor game in the modern era of the NBA.

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