HISTORICALLY, Colorado's economic booms came in metallic colours—gold, silver and uranium silvery-grey. But nowadays it is agricultural-green and sweeter-smelling. The reason is a well-established and regulated medical marijuana market, probably the most sophisticated in America with nearly 128,000 card-carrying patients, 730 shops and 1,100 cultivators, a third of which are in Denver alone. For Jessica LeRoux, owner of Twirling Hippy Confections, it means a decent living making pot-infused cheesecakes with varieties like “Chocolate Euphoria” and “January Hot Toddy”. Other pot entrepreneurs, meanwhile, are making millions and have a group of slick lobbyists. One alternative newspaper in Denver has a pot shop reviewer.

While it is allowed in some form in 16 states and Washington, DC, Colorado is the leader in trying to make medicinal pot a legitimate business. It has been legal since a voter-approved amendment to the state constitution in 2000, but the for-profit side only took off two years ago after the legislature allowed individual counties and towns more flexibility in interpreting the rules. Over a hundred have done so.

Pot proponents argue that the new rules should allay fears of illegal usage and crime. A new state enforcement division mandates high levels of security and a 24-hour agent-monitored video feed in all shops and facilities. Each plant's weight is recorded and electronic tags follow their produce from “seed to sack”, everything documented along the way.

Now emboldened, advocates want Colorado to allow recreational use too, using a similar regulatory structure. Boosted by money from national organisations, a signature campaign is under way to put it to a vote in 2012 (a relatively easy thing to do) and the effort has already overcome two legal challenges. It might just pass; a recent poll showed 51% in favour and 38% opposed, even though some neighbourhood groups worry that Denver will turn into Amsterdam.

The shadow of the criminal law still threatens a bad trip, however. In October, California's four federal prosecutors threw the state (and drug-lovers everywhere in the country) into confusion when they announced their intention aggressively to go after landlords who rent their buildings to dispensaries of medical marijuana, and even after newspapers, radio and television stations who accept advertising from sellers of the weed. Those threats came after federal agents raided growers of cannabis in several Californian counties during the summer, destroying about half a million pot plants and arresting more than a hundred people. For the Obama administration, which had signalled early in its term that it would not enforce marijuana laws in states that took a lenient approach to cannabis, this crackdown amounts to a puzzling U-turn; lawsuits are already trying to block the crackdown.

In California it seems especially bizarre, and it has not been echoed in Colorado. Californian voters were the first, in 1996, to legalise marijuana for medical purposes. Californians, meanwhile, continue to flirt with outright legalisation of the weed. A ballot initiative to this effect narrowly lost in last year's election, but a new effort is already under way. In October even the California Medical Association, which represents the state's doctors, called for legalisation. Meanwhile, a new law makes possession of less than an ounce merely an infraction, rather like a traffic ticket. The path to bliss is not easy.