"Historically, as soon as women really start to create a [gender] gap, a marijuana measure gets killed," says Allen St. Pierre, executive director of National Organization for the Reform of Marijuana Laws. "If women get weak-kneed, the men will start to drop."

Armed with that knowledge about why previous attempts had failed, campaigns in both Washington and Colorado set out to court women. Their efforts appear to have paid off. Both states approved measures legalizing marijuana with the backing of some 55 percent of the electorate. That was stronger than even proponents expected -- they had been cautiously optimistic about the Washington vote, but the Colorado measure appeared to be fading down the stretch. (Advocates in Oregon, where a marijuana-legalization measure failed on Tuesday, faced larger problems than merely enlisting females -- too little time to canvass, too few funds to spend.)

"We definitely wanted to reach women. We were very much focused on not being a pro-pot campaign but a pro-policy campaign."

Convincing women -- mothers, especially -- that legalization wasn't simply about stoners and libertarians was essential to ending blanket prohibition. They needed to be assured this was sound policy and that their children would not be affected.

"We definitely wanted to reach [women]," says Tonia Winchester, the outreach director behind the Yes on I-502 camp. "We were very much focused on not being a pro-pot campaign but a pro-policy campaign, showing that we could shift resources from incarcerating and focus on programs we knew would work."

With the female demographic in mind, both states went about crafting campaigns tailored to assuaging concerns like family safety and preventing access to drugs for children. In addition to emphasizing the basic premise of a tax-and-regulate system -- that is, that all marijuana would only be available through licensed dealers -- Washington ensured that a tight per se DUID policy dictating that a driver may carry no more than five nanograms of THC per milliliter of blood, would be included as part of I-502 (per se DUID laws make it illegal to drive with a certain amount of a controlled substance in the blood, regardless of whether impairment is apparent). By delineating a maximum threshold for drug level in the blood system, female support in Washington, according to St. Pierre and Winchester, remained strong.

While a similar per se DUID bill died in the Colorado Legislature earlier this year -- it is already illegal within Colorado to drive while intoxicated, but there is no specific threshold for drug levels in blood -- Mason Tvert, director of the state's pro-legalization campaign, made sure his campaign emphasized how Amendment 64's passage would benefit both public health and public coffers.

"We ran a very smart campaign: highlighting the benefits of keeping marijuana out of hands of young people, really generating tax revenue to benefit state and public schools, allowing law enforcement officials to focus on more serious crimes," Tvert says. "I think women, just like most men, agreed these were compelling reasons."