As of March 2011 there were laws in seven U.S. states that made it legal to sell and use marijuana for medicinal purposes. Those states were California, Colorado, Michigan, Montana, New Mexico, Oregon, and Washington. Four additional states and the District of Columbia are scheduled to open markets for medical marijuana before the end of 2011: Arizona, Maine, New Jersey and Rhode Island. The laws regulating the sale and use of marijuana in these states vary widely which makes tracking the market a complicated task. But as a fast growing market the motivation to track it is present and the task is made easier by the fact that marijuana is a highly regulated commodity and is therefore tracked carefully by most of the states in which its use for medical purposes is legal.

Today’s market size is the estimated value of marijuana sold legally in the United States. As a point of comparison, and according to the source, the sale of Viagra in the United States in 2010 was valued at $1.93 billion.

Geographic reference: Select states within the United States
Year: 2011
Market size: $1.7 billion
Source: Wayne Heilman, “Report: Medical Marijuana Sales to Reach $1.7B This Year,” The Gazette, Colorado Springs, March 24, 2011, available online here.
Original source: See Change Strategy and Medical Marijuana Markets