The US needed a lot of morphine during WW2. So it bought all the morphine Mexico could produce. After the war they were left with lots of crops but no legal ma

The US needed a lot of morphine during WW2. So it bought all the morphine Mexico could produce. After the war they were left with lots of crops but no legal market for them. This led many of them to turn to the illegal market. Cartels pay a lot of money in bribes and security which will not be necessary with legalization. It is possible they just become legal growers.