Final answer:
The NBA and ABA merged in 1976, which was a major event in professional basketball, leading to the consolidation of talent, the introduction of new game features, and stabilization within the sport.
Step-by-step explanation:
The NBA and ABA merger took place in 1976. This merger was significant in the history of professional basketball in the United States as it not only consolidated the talent pool but also led to the introduction of some innovative features from the ABA into the NBA, such as the three-point line and the All-Star Game dunk contest. The merger facilitated an expansion of teams and helped stabilize the financial and competitive landscape of professional basketball.