They'll be voting on whether to let farmers grow marijuana's far less potent cousin — hemp — for clothing, food, biofuel and construction materials among other uses.
But don't expect farmers to start growing it, at least not immediately. The passage of the measures would create the familiar clash with federal law, which prohibits growing the plant for industrial, recreational or medicinal purposes.
Farmers who say they have enough to worry about with drought and crop diseases don't want to also be left wondering whether federal drug agents will come knocking.
"Farmers are already engaged in a high-risk endeavor," said Roy Kaufmann, a spokesman for Oregon's pot initiative. "That weariness of potentially facing federal action is just too much of a disincentive."
The three ballot initiatives to regulate pot like alcohol have garnered much attention, in part for the hundreds of millions of dollars they could bring into state coffers and for the showdown it could set up with the federal government.
No state has made recreational pot legal, and these measures would be the first to set up state-sanctioned pot sales. The Justice Department could try to block them in court under the argument they frustrate federal antidrug law enforcement efforts.
Less well known is the effect the measures would have on hemp and the possibilities they create for another fight with the federal government.
Nine states — Hawaii, Kentucky, Maine, Maryland, Montana, North Dakota, Oregon, Vermont and West Virginia — have passed laws allowing hemp cultivation or research, and supporters of the latest measures say they would be another shot across the federal government's bow.
Oregon's earlier law, passed in 2009, allows the state to regulate hemp production; the initiative on the ballot next month, Measure 80, would allow unregulated hemp production.
While medical marijuana patients and those who grow for recreational use have been willing to risk federal prosecution, a viable hemp crop would be much larger than many of those grow operations, putting farmers at risk of severe mandatory minimum sentences in federal court.
Hemp and marijuana are the same species, cannabis sativa, but are genetically distinct. Hemp has a negligible content of THC, the psychoactive compound that gives marijuana users a high. It's also grown differently, in tightly packed plots to maximize stalk height rather than widely spaced to maximize branching and flowering.
Marijuana growers generally don't want their plants anywhere near hemp fields because cross-pollination would create less potent marijuana, so the notion of farmers hiding marijuana plants among their hemp crop isn't much of a concern.
But Steve Freng, prevention treatment manager for the Northwest High Intensity Drug Trafficking Area, a federally funded antidrug effort, said having legalized hemp would nevertheless make marijuana enforcement trickier.
"What comes to mind immediately is how difficult it would be to regulate and oversee an industry like that," he said. "At this point in states that have medical marijuana, a good amount of marijuana is overproduced. It's not unusual for growers to sell out of state."
Freng questioned whether there's a serious market for hemp in the U.S.
A Colorado corn farmer who serves in the state Legislature, Republican state Sen. Greg Brophy, suggested hemp's commercial potential could be hampered by high prices for corn, wheat and soybeans. Growing corn right now is "like owning your own ATM," he said.
For most of U.S. history, hemp was an important agricultural product used for rope, fabric and even the paper Thomas Jefferson used to draft the Declaration of Independence.
But competition arose, first from the cotton gin, which made cotton easier to process, and then from synthetic fibers in the early 20th century. Americans became more concerned about the availability of marijuana, and the federal government imposed severe restrictions on hemp.
There was a brief resurgence during World War II, when the U.S. Department of Agriculture launched a "Hemp for Victory" campaign to replace Southeast Asian fiber sources cut off by the Japanese, but there has been no commercial hemp production in the U.S. since the 1950s, according to a January report from the Congressional Research Service. Technically, the DEA is authorized to grant farmers special permits to grow hemp. It just never does.
At least 30 countries produce hemp commercially, and most of the hemp imported into the U.S. is grown in China, Canada and Europe.
Rough industry estimates suggest that a few hundred million dollars' worth of hemp products, such as soaps, body lotions and hemp granola, are sold in the U.S. every year.
All of it is imported, which maddens David Bronner, chief executive of Dr. Bronner's Magic Soap based in Escondido, Calif. His company uses 20 tons of hempseed oil in soaps every year and has contributed $50,000 to Washington's campaign and $50,000 to Colorado's.
"The Canadian farmers are laughing at us all the way to the bank," Bronner said. "We give $100,000 a year to the Canadians. If American farmers could grow industrial hemp here, we'd recognize 25 percent savings, for sure."
That kind of talk intrigues farmers like Ted Durfey, who has a seed press at his Sunnyside, Wash., farm to help turn the canola and flax he grows into biofuel.
"If it's sanctioned, it would lend itself pretty well to enhancing our local economy," Durfey said. "But I'm definitely not going to grow a commodity that's illegal under federal law."
Another central Washington farmer, Tom Stahl, said that if the initiative passes, he'd likely grow it until federal authorities caught on and warned him not to.
But even some farmers interested in experimenting with hemp aren't necessarily planning to vote for the ballot measures. They include Rob Jones, a southern Colorado potato farmer who has unsuccessfully lobbied the Legislature to permit industrial hemp.
Told the marijuana measure on ballots this fall would do the same thing, Jones scoffed. "It's going to be legal to smoke it in this state before we can grow it for legitimate purposes," Jones said.