The cannabis plant had been used by humans as medicine and enjoyed for its psychoactive properties for thousands of years, but in 1937 it came under strict federal regulation in the United States. Harry J. Anslinger, the first commissioner of the Federal Bureau of Narcotics — who made some notoriously racist comments — waged war on cannabis, also called “reefer” or “marihuana,” Mexican slang for “the weed that intoxicates.” In 1971 President Richard Nixon declared a “war on drugs,” and every federal administration since has continued the campaign. Despite this, almost all Americans now live in states where cannabis is legal to use in some form as medicine, and in eighteen states it’s legal for adults to use for recreation. It is regulated and taxed by state and local governments, which often spend that revenue on badly needed social services. Medical cannabis is used to treat multiple sclerosis, epilepsy, Parkinson’s disease, nausea caused by cancer treatments, and other ailments.