The US was resposible for the drug war thay happened in Colombia in the 1960's all the way to the present day. The Colombians used to smuggle drugs directly from their country to Miami. But after years, using the same route was a risk and they needed help from the Mexicans. Now, Colombians send shipments to Mexican Cartels and they pass the drugs from Mexico to the US. The US is ti blame because of the Massive drug consumption and they selling pf weapons to Mexican cartels
Since a large percentage of the drugs that we use in the United States come across the border, I think that the money they make from selling drugs here and the bans that we have on drugs here that make smuggling them in profitable have a lot to do with the industry existing.
In the industry, everything is made by someone's need of it and is not the exception for drugs. The smuggling of drugs started in south America, and the direct route is through Mexico. People in the Mexican country saw that it was better to sell than to export so they started their own cartel. As more and more people saw the amount of money that you can get, more cartels where created. The cartels soon became even more powerful than the Mexican government since they couldn't handle them.