The history of cannabis in the United States is a complex journey shaped by shifting social attitudes, political movements, and evolving laws. From early 20th-century prohibition to the sweeping legalization efforts of the 21st century, cannabis policy has reflected broader debates about medicine, criminal justice, and individual freedom. This timeline traces key moments in U.S. cannabis history—highlighting landmark legislation, court rulings, and cultural turning points that have shaped how the country views and regulates the plant today.
This is a work in progress.
United States - Dec. 2, 2022
The Medical Marijuana and Cannabidiol Research Expansion Act was signed into law, making it easier to conduct medical research on cannabis. It is the first standalone cannabis reform legislation ever enacted at the federal level.
United States - Dec. 20, 2018
The 2018 Farm Bill, signed into law on December 20, 2018, marked a major shift in U.S. cannabis policy by legalizing industrial hemp at the federal level. For the first time since 1937, hemp—defined as cannabis containing less than 0.3% THC—was removed from the Controlled Substances Act, effectively distinguishing it from marijuana. The bill allowed farmers nationwide to grow and sell hemp commercially, and it opened the door for expanded research, interstate commerce, and crop insurance for hemp producers.
United States - Dec. 16, 2014
After six failed attempts, the Rohrabacher-Farr amendment passed the House and became law in December 2014 as part of an omnibus spending bill. Originally introduced by Rep. Maurice Hinchey in 2001, it prohibits the U.S. Department of Justice from using federal funds to interfere with state medical cannabis laws. It marked the first time either chamber of Congress voted to protect medical cannabis patients, representing a historic milestone for federal cannabis reform. However, the amendment does not change the legal status of cannabis and must be renewed each fiscal year to remain in effect.