Legal marijuana is already big business in America. Colorado alone sold more than $700 million worth of legal weed in 2014, its first full-year of legal recreational and medical sales. Three other states and the District of Columbia have legalized recreational marijuana. Twenty-three states and Puerto Rico have legalized medical marijuana, and revenue for the industry as a whole has been growing nearly 34% a year for the past five years. And it’s only expected to keep growing.