NEW YORK -- Voters in three states will decide next month whether to legalize the sale and use of marijuana. If a ballot measure in one of those states succeeds, as supporters predict, it may create a rare truce in the war on drugs -- and trigger a showdown with the federal government.

State-level legalization would climax decades of struggle by reformers to convince voters that marijuana presents less of a threat to public safety than legal drugs, including alcohol. It would also show that pro-pot activists have learned from previous losses, like California's Proposition 19.

"There's no doubt in my mind that at least one of them will pass," said Dan Riffle, a legislative analyst for the Marijuana Policy Project.

His confidence appears justified. A September poll put support in Washington state at 57 percent. A Colorado poll out Monday from The Denver Post showed 48 percent in favor, versus 43 percent opposed. Support in Oregon was lagging.

Proponents have picked their battles. Legalization is only on the ballot in libertarian-leaning western states. Still-hostile state legislatures have been bypassed with ballot initiatives. And the presidential election will draw marijuana- friendly younger voters to polls.

Public support for marijuana legalization has been on a long-term upward curve, with a majority of Americans saying for the first time last year they favored it.

Translating that sentiment into success at the ballot box, however, has been difficult. Medical marijuana has the public relations advantage of using cancer victims as spokespersons. But legalizing marijuana for all adults has often been defined by opponents, who raised the specter of drug dealers and impaired drivers in California in 2010.

So in Washington state, where legalization is most likely to be approved, reformers carefully crafted the initiative to account for concerns from law enforcement officials. They have also made heavy use of former U.S. Attorney John McKay, who speaks credibly to public safety concerns.

"Essentially it was about building a relationship of trust," said Allison Holcomb, drug policy director for the state chapter of the American Civil Liberties Union, who leads the campaign to pass the legalization ballot measure, known as Initiative 502.

The ACLU carefully poll-tested provisions of the initiative. An intoxication standard for marijuana's intoxicant was created to defuse concerns about users driving under the influence. Instead of leaving regulation up to municipalities, as would have been done under California's failed proposition, a single, statewide standard would be put in place.

The "libertarian wet dream of legal pot with no regulations" does not play well with voters, said Riffle.

Rather, people want safeguards. They also want to see a different kind of green. All three measures emphasize taxing marijuana sales to produce revenue for cash-strapped states. In Washington alone, the state's Office of Financial Management estimated that legalization could bring as much as $2 billion over five years in taxes.

Nothing in the evolution of the pro-pot movement will deter legalization opponents from trying to stop the ballot measures.

In Colorado, support for legalization seems to have dipped since last month. That's not unusual for ballot measures as Election Day approaches. But Laura Chapin, the spokeswoman for No on 64, said it shows her side's arguments are winning.

"I think a lot of that is due to people understanding that amending the Colorado Constitution to fully legalize recreational marijuana and create a marijuana industry in this state brings with it a lot of problems," Chapin said.

Marijuana opponents in Colorado have pointed to the standard issues of health and safety, but Chapin said they have also highlighted the appropriateness of the amendment method. "This is a case where the how matters as much as the why."

Nationally, drug warriors warn of a "constitutional confrontation" if states legalize marijuana sales.

"Federal law, the U.S. Constitution and the Supreme Court decisions say that this cannot be done, because federal law preempts state law," said Peter Bensinger, who headed the Drug Enforcement Administration under Presidents Gerald Ford, Jimmy Carter and Ronald Reagan.

The Obama administration has rejected legalization in the past. but this election season, it has been silent on the topic. Pro-pot activists acknowledge that if President Barack Obama -- or Mitt Romney -- wanted to stop the collection of marijuana tax revenue, they likely could.

"There's a whole regulatory structure that this sets up, and if the federal government so chooses they can interfere with that," said Riffle. But he warned that if the feds did so, they would clash with the will of voters in the "laboratories of democracy" -- and against a very popular earmark in the Colorado measure.

"Essentially every action from the federal government there would mean hundreds of millions of dollars that wouldn't go to schools," Riffle said.

Voters, so far, seem unconcerned by the prospect of federal action. Travel author and television personality Rick Steves, a supporter of the Washington measure, said he has received support from across the political spectrum during his barnstorming tour of the state.

Steves pointed to Portugal, where problematic drug use has reportedly dropped by half since drugs were decriminalized in 2001, as an example of the positive change. And no, he added, Washington state will not start to look like another European destination if it legalizes marijuana.

"I don't foresee any Amsterdam kind of mecca here," Steves said. "I just see less people in jail and more social justice."

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  • $13.7 Billion Saved On Prohibition Enforcement Costs

    The government would save an estimated $13.7 billion on prohibition enforcement costs and tax revenue by legalizing marijuana, <a href="http://www.huffingtonpost.com/2012/04/17/economists-marijuana-legalization_n_1431840.html" target="_hplink">according to a paper endorsed by 300 economists</a>.

  • Marijuana Inmates Cost Prisons $1 Billion A Year

    Inmates incarcerated on marijuana-related charges cost U.S. prisons $1 billion annually, according to a 2007 study, <a href="http://www.alternet.org/rights/47815/" target="_hplink">AlterNet reports</a>.

  • Marijuana Prohibition Costs Taxpayers $41.8 Billion A Year

    Including lost tax revenues, a 2007 study found that enforcing the marijuana prohibition costs tax payers $41.8 billion annually, <a href="http://www.forbes.com/2007/09/29/marijuana-laws-work-biz-cx_qh_1001pot.html" target="_hplink">Forbes</a> reports.

  • California Marijuana Crop Worth $14 Billion A Year

    Marijuana growers account for <a href="http://www.time.com/time/nation/article/0,8599,1884956,00.html" target="_hplink">$14 billion a year in sales in California</a>, making it the state's most valuable cash crop, TIME reports.

  • Illegal Marijuana A $36 Billion A Year Industry

    It's estimated that <a href="http://madamenoire.com/106691/capitalizing-on-the-billion-dollar-marijuana-industry/" target="_hplink">illegal marijuana is a $36 billion industry</a> in the U.S., MadameNoire reports.

  • One-Third Of Americans Think Legalization Would Boost The Economy

    About one-third of Americans say they think <a href="http://www.huffingtonpost.com/2010/04/20/legalizing-pot-will-not-b_n_544526.html?" target="_hplink">legalizing marijuana would boost the economy</a>, according to a 2010 poll by Associated Press-CNBC.

  • Dispensary Ads Boost Newspapers' Revenue

    The <em>Sacramento News and Review</em> saw a big boost in ad revenue when it offered advertising space for more than 60 medical marijuana dispensaries, enabling the publication to hire three additional employees, <a href="http://www.news10.net/news/local/article/144285/2/Marijuana-ads-mean-big-money-for-weekly-newspaper" target="_hplink">according to News 10</a>.

  • Mendocino Zip Tie Program Raised $600,000

    Mendocino County, California's zip tie program aimed at regulating medical marijuana growing by charging permits for each plant raised <a href="http://www.huffingtonpost.com/2012/01/09/medical-marijuana-license-mendocino_n_1193198.html" target="_hplink">$600,000 in revenue in for the Sheriff's department</a> in 2011.

  • Oakland Raised More Than $1 Million In Marijuana Tax Revenue

    The city of Oakland, California raised $1.3 million in tax revenue from medical marijuana dispensaries in 2011, 3 percent of the city's total business tax revenue, according to <a href="http://www.nytimes.com/2012/02/12/us/cities-turn-to-a-crop-for-cash-medical-marijuana.html?_r=1" target="_hplink"><em>The New York Times</em></a>.

  • Colorado Pulls In $5 Million From Pot Sales Tax

    In 2011, Colorado pulled in $5 milllion in sales taxes from medical marijuana businesses, <a href="http://www.nytimes.com/2012/02/12/us/cities-turn-to-a-crop-for-cash-medical-marijuana.html?_r=1" target="_hplink"><em>The New York Times</em></a> reports.

  • Legal Marijuana Could Be $100 Billion Industry

    Economist Stephen Easton estimated in 2010 that <a href="http://www.businessweek.com/debateroom/archives/2010/03/legalize_mariju.html" target="_hplink">legal marijuana could be a $45 to $100 billion industry</a>, <em>Bloomberg Businessweek</em> reports.

  • Each weGrow Center Creates 75 Jobs

    When hydroponic marijuana growing supply chain weGrow opens a new store it <a href="http://aznow.biz/small-biz/wegrow-phoenix-opens-cultivates-opportunities-arizona)" target="_hplink">creates an estimated 75 jobs</a> indirectly, according to AZBusiness Magazine.

  • Majority Of States Support Taxing Marijuana

    More than <a href="http://www.huffingtonpost.com/2010/04/20/legalizing-pot-will-not-b_n_544526.html?" target="_hplink">60 percent of states agree with taxing marijuana</a>, according to a poll by Associated Press-CNBC.

  • Marijuana Affects Workplace Motivation

    A Norwegian study 25 years in the making came to the shocking conclusion that <a href="http://www.huffingtonpost.com/2012/02/24/marijuana-use-has-adverse-affect-workplace-motivation_n_1300278.html?" target="_hplink">frequent marijuana use lowers employees' motivation at work</a>.

  • More Than 1,000 Dispensaries In California

    There could be more than 1,000 medical marijuana dispensaries operating in California, <a href="http://www.pasadenaweekly.com/cms/story/detail/how_does_your_pot_grow/8070/" target="_hplink"><em>Pasadena Weekly</em></a> reported in 2009.

  • Denver Counts More Dispensaries Than Starbucks

    As of July 2011, the city of Denver <a href="http://www.huffingtonpost.com/2011/07/06/medical-marijuana-denver-starbucks_n_891796.html" target="_hplink">counted more medical marijuana dispensaries than Starbucks franchises</a>.