Drug Market Shifts Away From Hard Drugs

A recent washington post article shows statistics that the war on drugs has moved from hard drugs such as cocaine and heroin to marijuana. Marijuana arrests have accounted for nearly half the total drug arrests in the entire nation. What I do not understand is why are dealers switching from hard drugs to marijuana when marijuana is so much cheaper. Of course, marijuana is the most widely used street drug in the nation, but there are still enough people out there that will still buy the hard drugs. It seems like dealers run the risk sometimes of getting caught when they sell marijuana because they have to sell so much of it to make any money.