Oregon today became the fourth US state to allow the recreational use of marijuana, amid a growing legalisation trend in the western United States.
The changes in the northwestern state's law come after voters in November approved a ballot measure making it legal to smoke, grow and own pot, though the drug remains illegal under federal law.
From now on, people in Oregon aged 21 and up can legally use marijuana for recreational purposes and grow up to four plants.
While marijuana remains illegal under federal law, more than 20 states have allowed it for medical use and many others are considering legislation to legalise it.
Alaska, Colorado and Washington state already allow recreational use under legislation similar to that now in force in Oregon.
According to a recent report by the ArcView market research group, 14 more US states will legalize recreational marijuana by 2020.
The nation's capital Washington has also voted to legalize pot but the US Congress, which has jurisdiction because the District of Columbia it houses is not a state, is trying to block the move.
Colorado's neighbors, Oklahoma and Nebraska, filed a lawsuit in the US Supreme Court in December protesting that the western state's legalisation of marijuana was harming them.
