Forget about what's happening in the partisan battle for control of Congress and statehouses across the country. The single-most important issue that will be decided on November 2 is California's Proposition 19, a ballot initiative that would legalize the cultivation, consumption, and sale of marijuana and allow municipalities to regulate and tax the stuff.

Though limited to voters in a single state, Prop. 19 is the only policy matter on the table with the potential to restructure the lives of virtually all Americans. If Prop. 19 passes, it will force, at long bloody last, an honest reconsideration of failed prohibitionist policies throughout the United States. In fact, given the drug war's influence on our foreign policy in Latin America and central Asia, Prop. 19's reverberations would even be felt far outside our borders.

Despite overt similarities to liquor prohibition in the 1920s, the drug war actually functions more like the Cold War used to. It's an almost-hidden, infrequently debated structuring device that affects every aspect of American politics, culture, and society. Just as Cold War anxieties transformed educational priorities and politicized everything from the Olympics to fluoridated drinking water, the drug war is everywhere with us. The same schools that plead poverty in teaching basic literature or math still all find time and money for D.A.R.E. and other drug-education classes, despite iffy results. Video games, public-service announcements, and even urinal-cake holders in men's rooms still implore us to just say no. Some 40 million workplace drug tests are administered each year, and even legal prescription drugs are getting some employees fired.

Marijuana has been illegal under federal law since the 1930s, so Prop. 19's passage would immediately trigger a constitutional showdown over whether states have the right to act as what Louis Brandeis called "laboratories of democracy." In the notorious 2005 medical marijuana decision Gonzales v. Raich, the Supreme Court ruled that federal law trumped state law when it comes to a person growing marijuana for personal use, but an affirmative state-wide vote for full-blown legalization will not be as easy to contain, despite Attorney Gen. Eric Holder's threat to "vigorously enforce" the Controlled Substances Act no matter the outcome. Legal precedent firmly establishes that state law enforcement agents are under no mandate to enforce federal laws, and the Dept. of Justice simply lacks the manpower to stop pot smokers at anything more than a symbolic rate.

A legalization win in California, or even a close call, will certainly spread to other states, including ostensibly conservative red states. A 2009 Zogby poll found that 52 percent of adults now agreed that pot should be regulated similar to alcohol, and other national polls all show persistently upward trends and historically high percentages sympathetic to legalization. Pot is the top cash crop in California, Alabama, Kentucky, West Virginia, and elsewhere. A dozen states, including California, Nebraska, Mississippi and North Carolina, have already decriminalized the possession of small amounts of marijuana, and more than that have legalized some form of medical marijuana (Arizona and South Dakota are voting on it this year too). Given marijuana's presence in every part of the country, legalization is not a question of if but when.

And because the young voters most passionate about legalization skew heavily Democratic (despite professional Democrats being reliably awful on the issue -- Sen. Dianne Feinstein leads the No-on-19 campaign), it is conceivable that Jerry Brown will be re-elected California governor because of the turnout Prop. 19 generates. That lesson will be on the minds not only of Democrats desperate to gin up any enthusiasm, but also pro-legalization Republicans eying the 2012 nomination, including Rep. Ron Paul (R-Texas) and former New Mexico Gov. Gary Johnson.

The growing desire for pot legalization is partly shaped by the recession and the need to pare back government spending on non-essential services while finding new sources of revenue. The $50 billion in direct costs of drug prohibition at all levels of government doesn't begin to capture the costs in social disruption, crime from black markets, foregone tax revenue, and more. The 858,000 marijuana-related arrests made each year -- many involving minors, non-violent offenders, and those possessing insignificant amounts -- accounts for more than half of all drug-related arrests and takes a huge toll on the criminal justice system and lower-income communities at every level. No one seriously questions that the drug war disproportionately impacts minorities and that most "drug-related" crime is in fact a result of the black market status of drugs. Mexican drug gangs may be violent but there is no reason to believe that Mexican marijuana merchants would be any more violent than Mexican mango merchants.

And make no mistake: The drug war is effectively a war on marijuana, by far the only illegal drug used by more 1 percent of the adult population on a regular basis. In 2009, the government reports that 6.6 percents of Americans used pot in the previous month; cocaine, the next-most popular, was used by only 0.7 percent.

Given that over 40 percent of high school seniors, close to half of all adults, and the three most-recent U.S. presidents have smoked pot, it's no surprise that a competitive legalization initiative is finally upon us. Prop. 19 would remove the nausea-inducing contradiction inherent in "decriminalization," which allows people to possess pot but not purchase it legally. As with the repeal of alcohol prohibition, another utopian ban that was widely flouted and increased all the miseries it purported to ameliorate, it would end the psychotic denial of the basic facts of how people choose to live.

More important, perhaps, the passage of Prop. 19 will set in motion the end of the larger drug war, just as the first few seemingly minor sledgehammer blasts on the Berlin Wall in 1989 eventually gave rise not simply to the end of the forced segregation of an occupied city or the demise of the German Democratic Republic, but two years later the collapse of the Soviet Union and international communism. To those who fear the end of the drug war, ask yourself two questions: Would your desire to use, say, heroin, change much if it were legal? And do you think that alcoholics would be more likely to seek help if they were criminals in addition to being substance abusers?

It may start in California, but the legalization of marijuana will also mean that schoolkids in Oklahoma won't have to pee in a bottle in order to be on quiz bowl teams and online vendors of bongs won't be prosecuted in Western Pennsylvania and medical marijuana patients in Florida will be able to concentrate on their cancer rather than their legal defense. It means covert farmers in Kentucky and Texas and Washington who generate billions of dollars worth of crops will fully enter the economy. It means that federal and state prisons all over the country will have room for violent prisoners. It means that cops will be deprived of their favorite means for shaking down "suspicious" low-income minorities, and it means that all Americans, even those who never use marijuana, will be more free.

That sort of change -- and dare we say it in Obama's America, hope -- is something no partisan swing in Congress or any other legislature could possibly top.

Nick Gillespie is editor in chief of Reason.tv and Reason.com. Matt Welch is the editor in chief of Reason magazine. They are coauthors of the book The Declaration of Independents: How libertarian politics can fix what's wrong with America, due out next year from Public Affairs.