California began selling recreational marijuana today in what’s seen as a milestone in the mainstreaming of the weed, and hundreds lined up to buy it.

Lines formed outside stores licensed to sell the drug long before opening hours, and store owners said they had stocked up in expectation of huge demand.

“It is probably our busiest day in our seven-year history,” said Matt Lucero, 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.”

California is the sixth state to allow sales of recreational marijuana, and as the nation’s most populous state, it’s 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.”

Pot remains illegal in the eyes of the federal government, and it is illegal to take marijuana across state lines, bring it on a plane or mail it.

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 United States in 2016, according to New Frontier Data.

California adults 21 and older can possess as much as an ounce and grow up to six plants at home as of Monday.