The trial of Joaquín “El Chapo” Guzmán, the infamous Mexican drug lord, has given the public an unprecedented look inside the operations of the Sinaloa cartel. Prosecutors have trotted out dozens of witnesses, including former cartel bosses, who have described how Mr. Guzmán and his associates built a multibillion-dollar narcotics empire.

The two months of testimony in Brooklyn federal court have revealed details about how the cartel smuggled cocaine, marijuana and other illegal drugs into the U.S. using cars, trains, planes,...