What are some geographic causes of the drug war in latin america?

For my world studies cl i have to right a report on a conflict in latin america and i am doing it on the drug war. for one part of my report we have to find and turn in ideas we could use to write it. I need 6 ways the geography of latin america is causing the drug war to keep going on. can someone please help me out and either give me an answer or a link to a website with an answer?