The three-point field goal was used under a trial basis during the 1979-80 regular season. The line is 22 feet in the corners extending to 23 feet, nine inches at the top of the key. Chris Ford of the Boston Celtics scored the first three-point field goal in NBA history with 3:48 left in the first quarter of the Celtics' 114-106 victory over Houston at Boston Garden (October 12, 1979).
The change was designed to open up the game and to add excitement
The three-point field goal had been tested in the NBA during the pre-season of the 1978-79 season and became a permanent rule at the start of 1980-81 season.
The three-point line (22 feet in the corners extending to 23 feet, nine inches at the top of the key) was shortened to a uniform 22 feet at the start of the 1994-95 season.
The change was designed to eliminate some of the congestion in the lane and lead to more scoring opportunities
At the start of the 1997-98 season, the three-point line, 22 feet from the basket, was lengthened to its original distance of 23 feet, nine inches, except in the corners, where the distance remained 22 feet. The change was aimed at improving the flow of the game and to add more spacing on the floor. Players defending the 3-point arc would not be able to easily drop down to "double-down," in the low post. With more one-on-one action developing in the low post, that would translate into higher-scoring games.
The American Basketball Association used the three-point field goal. At the time NBA leaders called it a gimmick. The three-pointer was suggested to the ABA by Bill Sharman. Sharman had seen it originated in the American Basketball League. (The American Basketball League played one full season (1961-62) and part of the 1962-63 season. George Mikan was also a proponent of the three-pointer and it was said he would have resigned as ABA commissioner if the rule wasn’t approved.
The shot's appeal was that it provides a bigger role the little man and opens up the middle.
In the NCAA, the line is set at 19' 9".
All field goals in the D-League are worth two points until the final five minutes of regulation and overtime when three-pointers are counted. This unique scoring rule first came into practice during the 2004-05 season.