The entire world. The drug trade is global and the USA is a huge market, perhaps the biggest.

Also worth reminding people that the whole point of money laundering is to keep the operations going without having to keep big secrets or make anyone unnecessary complicit. It's not about corruption, shady business, or legislation. Those are all lies told to get normal people to believe even uglier lies. No, it can all be completely reformed, swamp drained, and regularly audited to be squeaky clean and still the money and drugs will continue to flow unimpeded. This is outside the scope of individual governments. Even if the USA and Mexico cooperated perfectly, the money is already clean before it hits their domestic banks and the smuggling is less about avoiding getting caught and more about overwhelming the system. This is why it's called a "war" on drugs.

Americans. But it’s more like the head-end of Americans paying cartels for drugs and in order to pacify the ass-end from complaining they, in collusion with Mexico, have to make it “look like” they are doing something about it.

The world drug trade.