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The nation's first recreational pot industry opened in Colorado on Wednesday, kicking off an experiment that will be followed closely around the world and one that activists hope will prove that legalization is a better alternative than the costly American-led drug war.

Business owners who threw their doors open for shoppers at 8 a.m. are looking for the fledgling industry to generate as much revenue as state officials hope it will. At least 24 pot shops in eight towns opened, after increasing staff and inventory and hiring security.

More than a dozen people waiting in line outside one shop in Denver, as snow fell around dawn. Musician James Aaron Ramsey, 28, was among them, having driven from Missouri. He played folk tunes with his guitar as he waited.

"I'm going to frame the receipt when I go home, to remind myself of what might be possible. Legal everywhere," Ramsey said, who had served a brief jail sentence for pot possession less than a year ago and was excited to legally buy weed.

Colorado and Washington state approved legal recreational pot industries in 2012, and Washington's will open later this year. They are being closely watched around the world because they are the first regulated, taxed pot industries.

Some countries have decriminalized the drug, and the Netherlands lets people buy and sell it, but it's illegal to grow or process it.

Just as shops opened Wednesday, the Denver police department tweeted, "Do you know the law?" and linked to city websites on state and local laws that include bans on public consumption, driving under the influence, taking marijuana out of state and giving pot to anyone under 21.

Shopper Jacob Elliott traveled from Leesburg, Va., to be among the first to buy legal pot. He said he wrote reports in college about the need to end prohibition of marijuana, but never thought it could happen in his lifetime.

"This breaks that barrier," he said.

Tinted windows on a black limousine idling outside a dispensary showed another side of the newly legal weed market — people eager to try legal marijuana, but not ready to be seen publicly buying it.

Addison Morris, owner of Rocky Mountain Mile High Tours, had 10 clients waiting inside who paid $295 for three hours of chauffeuring by a "marijuana concierge" who would help them choose strains and edible pot products.

"We're your grandmother's pot connection," the 63-year-old said. "We're not the hippie stoners who are going to stand in this cold and party."

Morris said she's booked through the end of February with out-of-state clients. Guests receive samples in designer bags before getting tours. She said she's selling discretion. Guests are asked to leave cameras at home.

Earlier, pot users welcomed the new year — and the new industry — by firing up bongs and cheering in a cloud of marijuana smoke at a 1920s-themed "Prohibition Is Over" party in downtown Denver.

Skeptics worry the industry will make the drug more widely available to teens, even though legal sales are limited to adults over 21. They fear that the increased availability will lead to a rise in drug abuse and crime.

Preparation for the retail market started more than a year ago, soon after Colorado voters in 2012 approved the legal pot industry. Washington state has its own version, which is scheduled to open in mid-2014. Uruguay passed a law in December to become the first nation to regulate pot.

Pot advocates, who had long pushed legalization as an alternative to the lengthy and costly global drug war, had argued it would generate revenue for state coffers and save money in locking up drug offenders.

Still, setting up regulations, taxation and oversight for a drug that's never been regulated before took some time.

Colorado set up an elaborate plant-tracking system to try to keep the drug away from the black market, and regulators set up packaging, labeling and testing requirements, along with potency limits for edible pot.

The U.S. Justice Department outlined an eight-point slate of priorities for pot regulation, requiring states to keep the drug away from minors, criminal cartels, federal property and other states in order to avoid a federal crackdown. Pot is still illegal under federal law.

Police in the eight Colorado towns allowing recreational pot sales stepped up patrols to dispensaries in case of unruly crowds. Denver International Airport placed signs on doors warning fliers they can't take the drug home in their suitcases.

With the additional police patrols, the airport warnings and various other measures, officials hoped they have enough safeguards in place to avoid predictions of public health and safety harm from the opening of the pot shops.

They are aware of how many people, from across the country and around the world, were watching. "We understand that Colorado is under a microscope," Jack Finlaw, lawyer to Gov. John Hickenlooper and overseer of a major task force to chart new pot laws, recently told reporters.

There was no shortage of skeptics worried retail pot would endanger the public. A group of addiction counselors and physicians said they're seeing more marijuana addiction problems, especially in youths, and that wider pot availability will exacerbate the problem.

"This is just throwing gas on the fire," said Ben Cort of the Colorado Center for Dependency, Addiction & Rehabilitation at the University of Colorado Hospital.

Not all marijuana users in Colorado are toasting the dawn of retail sales.

Some medical marijuana patients groups say they're worried about supply. That's because the retail inventory for recreational use is coming entirely from the preexisting medical inventory. Many in the industry warned patients to stock up before the sales began.

It was too soon to tell whether prices were going up.

For now, medical patients should have plenty of places to shop. Most of Colorado's 500 or so medical marijuana shops haven't applied to sell recreational pot, and many that have plan to serve both recreational and medical patients

Marijuana activists were hoping Colorado's grand experiment wouldn't be that noticeable after an initial rush of shopping.

"Adults have been buying marijuana around this country for years," said Mason Tvert, spokesman for the Marijuana Policy Project. "The only difference is that in Colorado they will now buy it from legitimate businesses instead of the underground market."

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