Final answer:
Since prohibition, the illegal drug trade has been the top revenue source for organized crime, surpassing illicit alcohol trafficking that was central during the Prohibition era.
Step-by-step explanation:
The number one money maker for organized crime since prohibition has been widely considered to be the illegal drug trade. During the Prohibition era, organized crime syndicates seized the lucrative opportunity to traffic illicit alcohol, resulting in a significant expansion of their activities and influence. Individuals such as Al Capone capitalized on the public's desire for alcohol, engaging in bootlegging, prostitution, gambling, and various forms of intimidation and violence to cement their power and expand their wealth. These criminal empires found ways to launder their income to disguise its illegal origins, making it challenging for law enforcement to track. Post-prohibition, the focus of organized crime shifted substantially toward the production, distribution, and sale of illegal drugs, which has remained a predominant source of revenue for crime syndicates worldwide.