The American Basketball Association (ABA) was a major men's professional basketball league from 1967 to 1976. The ABA ceased to exist with the American Basketball Association–National Basketball Association merger in 1976, leading to four ABA teams joining the National Basketball Association (NBA) and to the introduction of the 3-point shot in the NBA in 1979. League history The ABA was conceived at a time stretching from 1960 through the mid-1970s when numerous upstart leagues were challenging, with varying degrees of success, the established major professional sports leagues in the United States. Basketball was seen as particularly vulnerable to a challenge; its major league, the National Basketball Association, was the youngest of the Big Four major leagues, having only played 21 seasons to that point, and was still fending off contemporary challenging leagues (it had been less than five years since the American Basketball League (ABL) shut down). According to one of the owners of the Indiana Pacers, its goal was to force a merger with the more established league. Potential investors were told that they could get an ABA team for half of what it cost to get an NBA expansion team at the time. When the merger occurred, ABA officials said their investment would more than double. The ABA distinguished itself from its older counterpart with a more wide-open, flashy style of offensive play, as well as differences in rules — a 30-second shot clock (as opposed to the NBA's 24-second clock, though the ABA did switch to the 24 second shot clock for the 1975–76 season) and use of a three-point field goal arc, pioneered in the earlier ABL. Also, the ABA used a colorful red, white and blue ball, instead of the NBA's traditional orange ball. The ABA also had several "regional" franchises, such as the Virginia Squires and Carolina Cougars, that played "home" games in several cities. The ABA also went after four of the best referees in the NBA: Earl Strom, John Vanak, Norm Drucker and Joe Gushue, getting them to "jump" leagues by offering them far more in money and benefits. In Earl Strom's memoir Calling the Shots, Strom conveys both the heady sense of being courted by a rival league with money to burn — and also the depression that set in the next year when he began refereeing in the ABA, with less prominent players performing in inadequate arenas, in front of