How the drug cartels work in the US

Reuters:

Federal agents arrested 25 people on Thursday in a drug and money laundering probe targeting a prison gang with ties to a Mexican drug cartel that allegedly smuggled drugs across south Texas.

The FBI and U.S. Drug Enforcement Administration said the four-year probe into the Texas Mexican Mafia netted 25 members and associates of the prison gang during operations primarily in Laredo, Texas, the busiest land port along the U.S.-Mexico border.

Two indictments in the case charge the gang's Laredo chapter with heroin, cocaine and methamphetamine trafficking, as well as money laundering.

Agents say the drugs were moved through south Texas and were distributed in San Antonio, Austin and Corpus Christi. Cash from the drug trafficking was then sent to the gang's associates in Mexico, which were not identified by authorities.
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Federal and state authorities have said Mexican drug cartels like the Zetas — founded in the late 1990s by Mexican paramilitary deserters in Nuevo Laredo, across the Rio Grande from Laredo — regularly use gangs like the Texas Mexican Mafia to carry out its drug trafficking activities in the United States.
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The Mexican Mafia has about 6,000 members so this is only a small dent in their operations.  They appear to be a cog in the machinery of Zeta and other cartel operations.