Them Rocky Mountains never seemed so high

Politicians in Colorado have reported that "the sky didn't fall in" when marijuana went on sale to the public for the first time on New Year's Day, leading to calls for the drug to be legalised in other US states.

In Denver and at ski resorts around Colorado, dozens of shops licensed to sell marijuana to anyone aged over 21 reported few problems.

Barbara Brohl, the director of Colorado's revenue department - which hopes to raise millions of dollars in taxes on the drug - said: "Is the sky falling? No, I don't think the sky is falling today. Everything's gone pretty smoothly."

Colorado's dagga law, which went into force at the stroke of midnight on January 1, is the most liberal in the world. It allows for anyone over the age of 21 to buy the drug over the counter and to legally possess up to 28g at a time. Under the new regulations Denver, already known as the "Mile High City" for its altitude, has overtaken Amsterdam as the West's most lenient dagga capital.

In the Dutch city, the drug remains technically illegal. Laws against possession outside designated coffee shops are still enforced.

The owners of Denver's 30 legal shops spent the first hours of 2014 engaged in spliff-rolling and weed-bagging, and entrepreneurial snack stalls were set up for the morning rush.

The lines of buyers were kept under close watch by police. But the officers were less concerned about disorderly pot shoppers than the pickpockets who would target them. Under US law, it is illegal to use credit cards for drug purchases. The crowds arrived with pockets full of cash.

Their dollars are the first of what the Colorado state estimates will grow to a $600-million (about R6-billion) industry. Colorado officials expect to take $67-million a year in taxes, and have committed the first $40-million to fund a new school-building programme.

The state is also bracing for a mass influx of tourists.

"Colorado is going to prove that regulating marijuana works, and it won't be long before more states follow our lead," said the Marijuana Policy Project, one of the groups that campaigned for the new law.

But opponents warn of a "Big Marijuana" industry that will grow to be as indifferent to public health as cigarette and alcohol companies.

Patrick Kennedy, son of Robert Kennedy and recovering drug addict, said states experimenting with legalisation were "canaries in the coal mine", adding: "We don't have to have other states go down this road and have to learn the same hard lessons."

The average price was estimated to be $185 for 28g.

Washington state is in the process of becoming the second to legalise the drug, and a dozen others are looking at the Colorado model, which involves raising funds for projects such as building schools.