DENVER — At 7:59 a.m. on Wednesday, a harried Jay Griffin shouted to the crowd pressed against the roped-off lines leading to his storefront counter: "One minute until we make history!"

Sixty seconds later, he and a handful of other pot shop retailers opened a new and closely watched chapter in the national debate over legalizing marijuana as Colorado became the first state in the country where small amounts of recreational pot can be legally sold in specialty stores.

Steve "Heyduke" Judish, a 58-year-old retired federal worker from Denver who prefers weed to booze, was the first customer of the day at Dank Colorado, a tiny shop tucked in a Denver industrial district. By opening time there were about 40 customers from as far away as Iowa and Minnesota who had waited for hours.

After a quiet start in the morning, lines swelled in the late afternoon under the close watch of security guards. City officials commented that even though lines at some stores snaked into the streets in chilly weather, the crowds were remarkably patient and, yes, mellow — a mix of young and old, mostly men.

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Judish peeled off $30 and walked away with one-eighth of an ounce of Larry OG, a potent strain of marijuana that connoisseurs like for its euphoric rush. He had put his name on a list to be first in line 14 hours earlier.

But really, he has been waiting 40 years for this legal buy.

"It's cool to be part of history," he said with a grin.

Not far behind him was Doug Little, 62, who had arrived in the predawn darkness. He too felt the baby boomer tug of history. "I smoked my first joint in 1969 in a dorm room at Michigan State. I never thought I would see this in my lifetime."

"Hi, buddy. You got your ID?" Griffin asked as Little approached the counter.

"I'd like a quarter Trainwreck and a quarter Sour Diesel," Little said, rattling off the strains like a sommelier at a wine tasting as he ordered by the partial ounce.

"The names are crazy," he admitted. His tab came to $169.57.

In November 2012, Colorado voters approved Amendment 64, making it legal for residents over 21 to buy small amounts of recreational marijuana. Washington state passed a similar measure, but officials there say they won't be ready to open stores until later this year.

Despite the excitement in retail shops, there were critics like Kevin Sabet, co-founder of Smart Approaches to Marijuana, or SAM, who called Wednesday's landmark event "the beginning of the era of Big Marijuana not unlike what we saw in this country with Big Tobacco."

"This is an industry that makes money off addiction," he said, adding that he was concerned that children would be targeted and swayed into thinking marijuana is harmless.

Sabet vowed to continue the fight against legalization in other states, saying, "We don't think legalization is inevitable."

Internationally, Uruguay has approved state-sanctioned marijuana sales, which are also not yet up and running. The Netherlands has long had an informal decriminalization policy, and patrons can buy marijuana products in Amsterdam coffee shops.

Still, Colorado is thought to be the first jurisdiction in the world where marijuana is openly sold in specialty pot shops and tracked by the government from seed to store.

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The Colorado venture is being closely watched in other states considering loosening their pot laws, including California, Oregon and Arizona.