<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The legal history of cannabis in the United States began with state - level prohibition in the early 20th century, with the first major federal limitations occurring in 1937 . Starting with Oregon in 1973, individual states began to liberalize cannabis laws through decriminalization . In 1996, California became the first state to legalize medical cannabis, sparking a trend that spread to a majority of states by 2016 . In 2012, Colorado and Washington became the first states to legalize cannabis for recreational use . </P> <Ul> <Li> 1937: The Marihuana Tax Act is enacted, effectively prohibiting cannabis at the federal level . Although medical use is still permitted, new fees and regulatory requirements significantly curtail its use . </Li> <Li> 1970: The Controlled Substances Act is enacted, officially prohibiting cannabis for any use (medical included) at the federal level . </Li> <Li> 1990: The Solomon--Lautenberg amendment is enacted . As a result, many states pass laws imposing mandatory driver's license suspensions for persons caught possessing cannabis, even if unrelated to driving . </Li> <Li> 2014: The Rohrabacher--Farr amendment passed the U.S. House and was signed into law . Requiring annual renewal, it prohibits the Justice Department from interfering with the implementation of state medical cannabis laws . </Li> </Ul>

When did the first state legalize recreational weed