"In 1968, the National Institute of Mental Health began funding a Drug Supply Program to provide researchers with compounds necessary to conduct biomedical research. Initially, the program focused on THC and other naturally occurring cannabinoids, and then gradually expanded to a wide range of compounds. (Since its beginning, the program has synthesized or obtained over 1,500 different compounds that have been supplied to over 2,500 researchers.) Cannabis was among the first substances to be made available through the Drug Supply Program for use by scientists conducting both nonhuman research and human research under a variety of investigational new drug protocols. It was grown through a contract with the University of Mississippi. With its establishment in 1974, NIDA became the successor to NIMH as the administrator of the cannabis contract and the sole U.S. source for legal cannabis."

Source

"Provision of Marijuana and Other Compounds For Scientific Research - Recommendations of The National Institute on Drug Abuse National Advisory Council," National Institute on Drug Abuse (Bethesda, MD: Department of Health and Human Services, National Institutes of Health, January 1998).
http://archives.drugabuse.gov…