The International Volleyball Association was a short lived co-ed professional volleyball league in the United States from 1975 to 1980. Like other major sports leagues in the United States, it had two geographic divisions. However, its teams were entirely in the west. It is one of the few examples of a professional sports league where men and women competed on the same teams.
In keeping with the “International” name, the league included one team, El Paso-Juarez Sol, which acknowledged both sides of the international twin town in its name.
Source; Wikipedia.
The league existed from 1975 to 1979 and was founded by media industry luminaries including David Wolper, movie producer and Barry Gordy of Motown. Wilt Chamberlain, NBA great played alongside top U.S. and international volleyball players.
Several groundbreaking rule changes in 1975 and some notably have been adopted more recently by international and U.S.volleyball sanctioning bodies.
Notable adopted rules include; serving area, allowable double hit on hard driven spike, blocking touch is not counted and the ball may be played by any part of the body.
Images from the original significant rule change document follows. These rule pages were typed on a typewriter before computers took over word processing.