The man behind the sport's origin is James Naismith. James was a Canadian physical education instructor at the International YMCA Training School in Springfield, Massachusetts. He invented the game as a mere physical indoor activity to keep a bunch of students preoccupied on a rainy day in the December of 1891.
James wrote 13 basic rules, nailed two peach baskets to the lower railing of a gym balcony and used a soccer ball for the game. The class was then divided into teams of 9 players each and basketball was born. Initially the baskets were sealed at the base. So every time the ball went in, it had to be retrieved manually. These were later removed.
The first public game was held in Springfield, Massachusetts on March 11, 1892. Six years hence, the first professional basketball league, the NBL (National Basketball League)was formed and it comprised of six teams. However, it was shunned in 1904 and what followed was a series of smaller championships.
There were other leagues that dominated the 1920s and 1930s. These were the Eastern Basket Ball League, Metropolitan Basketball League and American Basketball League
June 6, 1946 witnessed the birth of the NBA (National Basketball Association) founded in New York. But then, it was known as the BAA (Basketball Association of America), until in 1949, when it was merged with the NBL to form the NBA. As of today, the NBA is the biggest professional basketball league in the USA.
Another alternative to the NBA, called ABA (American Basketball Association) was formed in 1967. It differed from the NBA by offering minor rule changes and a slightly different gameplay style. But it couldn't sustain for long and it was merged with the NBA.