Hundreds of people lined up outside stores in Nevada, as it became the fifth US state to legalise the sale of recreational marijuana.
Products for smoking and eating legally went on sale on Saturday – though consuming it in public, including in hotels, remains illegal.
Anyone who breaks the rule will face a $600 fine.
Chief executive of Essence Cannabis Dispensaries, Armen Yemenidijan, called it an “historic” day.
Among those first in line to make a purchase was State Senator Tick Segerblom, who has been one of the main proponents of legalisation in Nevada.
Nevada joins Colorado, Oregon, Washington and Alaska in relaxing the law to allow adults to buy the drug.
However, marijuana still remains officially banned by the federal government.
I’m so excited for this day. A lot of times I never thought it would happen, but now that it’s here, let’s take advantage of it.
Nevada’s the perfect place – it fits our lifestyle so well, it fits our tourism industry so well.
And I think that quickly… Nevada’s going to be looked upon as the gold standard for marijuana or cannabis and the whole country and the whole world’s going to come here when they want to experience it.