Lines formed outside stores licensed to sell the drug long before opening hours on Monday, and store owners said they had stocked up in expectation of huge demand, reports CNN.
"It is probably our busiest day in our seven-year history," said Matt Lucerno, the owner of Buddy's, a dispenser of medical-use marijuana in San Jose that holds the first license issued by California to also sell recreational marijuana.
"We have folks outside; every chair in the building is filled right now."
At Harborside dispensary in Oakland, hundreds lined up to be the first to buy the legal weed.
Speaking to CNN, Lucerno said he expected a 30 per cent bump in sales overnight, but "it looks, in looking around this room, more like 50 to 60 per cent".
California is the sixth US state to allow sales of recreational marijuana, and as the nation's most populous state, it is widely seen as a tremendous boost to mainstreaming marijuana.
"Cannabis is now legal in the most populous state in the country," New Frontier Data, which tracks the cannabis industry, wrote in its 2017 annual report, "dramatically increasing the total potential size of the industry while establishing legal adult use markets across the entire US Pacific Coast given the legalized states of Washington and Oregon".
The California industry is forecast to reach $7 billion in a few years, more than the $6.6 billion of the entire legal cannabis market in the US in 2016, according to New Frontier Data.
California adults aged 21 and older can possess as much as an ounce and grow up to six plants at home, CNN reported.
Massachusetts will begin selling retail marijuana on July 1. Maine has approved it, but there is no set date to begin sales.
Other states that allow the sale of recreational marijuana are Colorado, Washington, Oregon, Alaska and Nevada.
More retail shops are certain to open soon in California.
The Bureau of Cannabis Control, which issues licenses from the state, had handed out about 200 by the end of last week, spokesman Alex Traverso said.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
