PORTLAND, Ore. >> Discounts on pot, free food for folks with the munchies and live music will usher in a historic day for Oregon and for marijuana advocates across the country Thursday, as recreational sales of the drug that is still illegal under federal law begin in the state.

Oregon is one of four states that have legalized the sale of recreational marijuana. It will start with far more dispensaries than did Colorado or Washington state, where pot shops have been up and running for more than a year. Alaska could begin retail sales next year.

Pot shops in Oregon that already sell medical marijuana have made big plans for the historic day — and hope there is enough supply to meet what is expected to be a huge demand.

“I’m just trying to basically stock up for maybe four or five times what the normal volume would be,” said Chris Byers, owner of River City Dispensary in the southern Oregon town of Merlin.

Some dispensaries will be opening just after midnight to get a head start on sales.

One store is offering a goody bag with T-shirts, but no free marijuana. Another will have a live band and 10 percent discounts. The marijuana review site Leafly will set up with food trucks at a handful of stores, giving away free meals to anyone who promotes the service on social media.

Several stores have erected billboards in Portland. A shop in Merlin is advertising on the radio.

Shoppers have one more incentive to buy early and often: Under Oregon law, pot purchases will be tax-free until January — a savings of up to 20 percent.

Under the state law approved last year by voters, possession of marijuana in limited quantities has been permitted since July 1. But there’s been no legal way to buy it.

In Washington and Colorado, which preceded Oregon in allowing legal marijuana sales, the first day of sales brought massive crowds, severe shortages and high prices.

More than 250 medical marijuana dispensaries in Oregon have told the state they’ll sell to recreational customers. By contrast, Colorado had 24 stores on Day 1. Washington had just four, and a year later, still has fewer than Oregon.

Oregon also has a robust supply of marijuana that’s grown to support medical marijuana users and the black market. Companies have invested in massive warehouses in Portland to grow the drug indoors, and southern Oregon has some of the nation’s best conditions for outdoor cultivation of marijuana.

Growers don’t face strict regulations yet, so the supply can more easily flow into retail stores than it did in Washington and Colorado.

Still, there’s concern. Summer has historically been a time of marijuana shortages in Oregon, and most of the outdoor crop isn’t ready to harvest. Indoor growers have had minimal time to ramp up production, since lawmakers only approved the Oct. 1 start date three months ago.

“I think there’s going to be a lack of supply for indoor flower,” said Shane McKee, co-founder of Shango Premium Cannabis, which is opening one of its three Portland-area stores at midnight. He expects recreational customers to demand indoor-grown marijuana, which can be tightly controlled to maximize the high and the flavor.

“There’s a lot of highly educated buyers here who have been spoiled with high-grade cannabis for years,” McKee said.

McKee, whose company grows its own product indoors, said he has prepared by stockpiling marijuana for weeks.

Green Oasis, which has two locations in Portland and more on the way, has prepared by trying to cultivate strong relationships with growers. People who spend at least $40 Thursday will get a 10 percent discount, co-owner Matthew Schwimmer said.

“We thought it was a good idea to give back to the community,” Schwimmer said.