It's harvest time again for the marijuana plant, and US drug eradication officers are busier than usual.

An ever-tightening southern border, high unemployment, and a steady, even growing, appetite for the illicit plant have all led to a surge in marijuana acreage in the country's chief pot-growing regions, law enforcement sources say.

In the first eight months of the year, local, state, and federal police chopped down 8 million plants worth about $22 billion on the street – a 14 percent increase from last year. Seizures of the farms have nearly doubled in Washington state alone. There has been no increase in overall enforcement efforts or funding.

In recent years, domestic pot production in some parts of the US had fallen due to more anti-drug agents in helicopters scouring the prime cultivation areas, including the hillsides of southern Appalachia and the Pacific Northwest, police say. Only between 20 to 40 percent of planted pot fields are ever harvested and sold due to US enforcement actions, says the Office of Drug Control Policy.

But rising unemployment seems to have given new impetus to the industry, officials say.

Driven by tough times

Especially in east Tennessee, Kentucky, and West Virginia, tough economic times may be motivating descendants of moonshiners to take the high risk and put spades in the earth.

Pocketing a street value of up to $2,000 per plant, a successful grower can quickly rise in local prominence – new trucks and boats popping up in poor areas are often a sign of successful cultivators, police say.

The illegal American pot harvest is worth about $35 billion a year, according to government estimates. In comparison, the 2007 bumper corn crop in the US was worth approximately $45 billion.

Illegal California growers, too, seem to have picked up production – a sign to some that while the US economy is struggling, the black market is growing.

Growing appetite

So is demand. The US Department of Health and Human Services reported Thursday in the annual National Survey on Drug Use and Health that the number of Americans who report "current use" of pot rose from 14.4 million in 2007 to 15.2 million in 2008.

Hard times and unemployment seem to have had no negative impact on consumption, said Ed Shemelya, chief of marijuana eradication for the Office of Drug Control Policy's Appalachian High Intensity Drug Trafficking Area, in an interview to the Associated Press. In fact, it's the other way around, he said.

Despite intense eradication efforts and anti-drug campaigns, Justice Department figures show marijuana consumption has stayed level over the last decade, agrees Bruce Mirken, a San Francisco-based spokesman for the pro-legalization Marijuana Policy Project in Washington.

"It may not be that people are spending their last money on marijuana, but certainly the fact is that the need to … distract yourself is pretty much a constant in human behavior through good times and bad," he says.