COLORADO became the "Amsterdam of America" yesterday, opening the first shops in the US to sell cannabis legally for recreational use.
As the state prepared for a wave of so-called "pot tourism", extra police officers were on duty in the capital, Denver, and officials sought to limit use of the drug in popular ski resorts amid safety fears.
There were also concerns that cannabis would be bought up and smuggled out of the state, leading to Denver International Airport introducing rules banning possession of the drug on its premises with fines of up to $999 (€725).
Under a law voted for by residents of Colorado in November 2012, known as Amendment 64, the state is allowing those over 21 to buy up to an ounce of cannabis at licensed shops.
The state is levying a 25pc tax, which, it has been estimated, could bring in nearly $100m (€73m) a year. A total of 348 retail licences have been issued.
Possession of the drug remains illegal under federal law but the US Department of Justice is allowing the Colorado experiment to go ahead.
In Denver, officials have adopted rules that will allow them to fine people smoking the drug in public places. They threatened to enforce such fines on people attending the largest planned New Year's Day cannabis party in the city. The "Cannabition" party was subsequently cancelled.
Matt Brown, the organiser, said: "It is unfortunate that the city of Denver has chosen to take such a hardline stand against the idea of adults assembling to legally celebrate the unprecedented milestone."
Cannabis is already legal for use by those with medical conditions in 19 US states. (© Daily Telegraph, London)