Driving north on the scenic highway 101 from San Francisco's Golden Gate Bridge, the terraced vineyards of Sonoma County give way to rocky foothills growing an open secret. Hidden among the rising slopes are groves of cannabis plants, a pillar of the local economy in this area known as the Emerald Triangle.

Marijuana has become an accepted part of the culture in the rural, sparsely populated region that spans the three counties of Mendocino, Humboldt and Trinity.

"The parks and the forest lands, they're just inundated with it," said Lieutenant Rusty Noe of the Mendocino County sheriff's office.

Local officials say pot accounts for as much as half of the regional economy in an area still reeling from the decades-long decline in the timber industry. In addition to marijuana sales, pot growing supports everything from garden supply stores to makers of plastic pipe.

Mendocino County Agricultural Commissioner Tony Linegar calls marijuana "a significant part of the economy - the businesses that are succeeding are the ones that are supplying this industry."

A sociology course this semester at Humboldt State University is focusing on "the growth of the marijuana economy," and a Ukiah clinic that prescribes medical marijuana sits next door to recruiting offices for the U.S. Air Force and the Marines.

Pot smokers brazenly light up joints on the steps of the Mendocino County courthouse, and pot plants in residents' gardens peek over schoolyard fences.

"The police say, and I quote, 'Do it where I can't see it or smell it,'" said 39-year-old Just, who is known by that single name.

Sheriffs in the Emerald Triangle concentrate on large-scale growing operations, many of which are in state and national parks.

Noe said his office tries not to hassle individuals who have a medical marijuana card, but will not tolerate growers who try to make a profit by cultivating far more than they need for medical purposes.

Medical marijuana use already is legal throughout California, and the U.S. Supreme Court rejected a move by two counties to bar patients from using the drug for medical purposes.

Now politicians are considering whether to take the next major step and decriminalize the drug altogether. Governor Arnold Schwarzenegger said recently the time is right for a debate on legalization, though he remains opposed to such a move.

State Assemblyman Tom Ammiano has introduced a bill that would make California the first U.S. state to treat marijuana the same as alcohol. His proposal would make the use or sale of marijuana legal to anyone 21 or older.

Ammiano points to a recent poll showing 56 percent of Californians favor legalizing and taxing marijuana. His bill would impose hefty taxes on marijuana sales that state officials estimate would bring US$1.3 billion annually to financially stressed California.

"With the state in the midst of an historic economic crisis, the move toward regulating and taxing marijuana is simply common sense," he said. "California has the opportunity to be the first state in the nation to enact a smart, responsible public policy for the control and regulation of marijuana."

California became the first U.S. state to allow the sale and use of marijuana for medical purposes in 1996 when voters passed Proposition 215. There are about 200,000 licensed medical marijuana users in the state. During the administration of former president George W. Bush, federal authorities routinely raided California medical marijuana dispensaries. Though it remains illegal to grow, buy, sell or possess marijuana under federal law, the administration of President Barack Obama said earlier this year it would not target California dispensaries.

Many law enforcement officials oppose such a change, and are against legalization. The California Police Chiefs Association released a report in April that said marijuana dispensaries are illegal under federal law "and should not be permitted to exist."

The group said such dispensaries invite more crime and "compromise the health and welfare of law-abiding citizens." But with state and local budgets facing huge deficits, many officials see marijuana as part of the solution.

The value of California's marijuana crop has been estimated by legalization supporters to be as high as US$14 billion annually.

Even if the actual value is only half that amount, it still would nearly equal the state's top cash crop and be double that of grapes, valued at US$3 billion a year.

The state already collects US$18 million a year in sales tax on medical marijuana. In Ukiah, a recent legalization rally drew only about a dozen supporters. Though some legalization advocates think marijuana could do for the Emerald Triangle what wine has done for the Napa Valley, many growers want to avoid taxes or government regulation. "I would be happy if the public acceptance level that came with legalization were there," said Just, who moved from Missouri to Northern California in large part because of its marijuana culture.