SAN FRANCISCO - On Monday, somewhere in New York City, 420 people will gather for High Times magazine's annual beauty pageant, a secretly located and sold-out event that its sponsor says will "turn the Big Apple into the Baked Apple and help us usher in a new era of marijuana freedom in America."
They will not be the only ones partaking: April 20 has long been an unofficial day of celebration for marijuana fans, an occasion for campus smoke-outs, concerts and cannabis festivals. But some advocates of legal marijuana say this year's "high holiday" carries extra significance as they sense increasing momentum toward acceptance of the drug, either as medicine or entertainment.
"It is the biggest moment yet," said Ethan Nadelmann, the founder and executive director of the Drug Policy Alliance in Washington, who cited several national polls showing growing support for legalization. "There's a sense that the notion of legalizing marijuana is starting to cross the fringes into mainstream debate."
For Mr. Nadelmann and others like him, the signs of change are everywhere, from the nation's statehouses - where more than a dozen legislatures have taken up measures to allow some medical use of marijuana or some easing of penalties for recreational use - to its swimming pools, where an admission of marijuana use by the Olympic gold medalist Michael Phelps was largely forgiven with a shrug.
Long stigmatized as political poison, the marijuana movement has found new allies in prominent politicians, including Representatives Barney Frank, Democrat of Massachusetts, and Ron Paul, Republican of Texas, who co-wrote a bill last year to decrease federal penalties for possession and to give medical users new protections.
The bill failed, but with the recession prompting bulging budget deficits, some legislators in California and Massachusetts have gone further, suggesting that the drug could be legalized and taxed, a concept that has intrigued even such ideologically opposed pundits as Glenn Beck of Fox News and Jack Cafferty of CNN.
"Look, I'm a libertarian," Mr. Beck said on his Feb. 26 program. "You want to legalize marijuana, you want to legalize drugs - that's fine."
All of which has longtime proponents of the drug feeling oddly optimistic and even overexposed.
"We've been on national cable news more in the first three months than we typically are in an entire year," said Bruce Mirken, the director of communications for the Marijuana Policy Project, a reform group based in Washington. "And any time you've got Glenn Beck and Barney Frank agreeing on something, it's either a sign that change is impending or that the end times are here."
Beneficiaries of the moment include Norml, the National Organization for the Reform of Marijuana Laws, which advocates legalization, and other groups like it. Norml says that its Web traffic and donations (sometimes in $4.20 increments) have surged, and that it will begin a television advertising campaign on Monday, which concludes with a plea, and an homage, to President Obama.
"Legalization," the advertisement says, "yes we can!"
That seems unlikely anytime soon. In a visit last week to Mexico, where drug violence has claimed thousands of lives and threatened to spill across the border, Mr. Obama said the United States must work to curb demand for drugs.
Still, pro-marijuana groups have applauded recent remarks by Attorney General Eric H. Holder Jr., who suggested that federal law enforcement resources would not be used to pursue legitimate medical marijuana users and outlets in California and a dozen other states that allow medical use of the drug. Court battles are also percolating. The United States Court of Appeals for the Ninth Circuit heard arguments last Tuesday in San Francisco in a 2007 lawsuit challenging the government's official skepticism about medical uses of the drug.
But Allen F. St. Pierre, the executive director of Norml, said he had cautioned supporters that any legal changes that might occur would probably be incremental.
"The balancing act this year is trying to get our most active, most vocal supporters to be more realistic in their expectations in what the Obama administration is going to do," Mr. St. Pierre said.
For fans of the drug, perhaps the biggest indicator of changing attitudes is how widespread the observance of April 20 has become, including its use in marketing campaigns for stoner-movie openings (like last year's "Harold & Kumar Escape from Guantánamo Bay") and as a peg for marijuana-related television programming (like the G4 network's prime-time double bill Monday of "Super High Me" and "Half Baked").
Events tied to April 20 have "reached the tipping point in the last few years after being a completely underground phenomenon for a long time," said Steven Hager, the creative director and former editor of High Times. "And I think that's symptomatic of the fact that people's perception of marijuana is reaching a tipping point."
Mr. Hager said the significance of April 20 dates to a ritual begun in the early 1970s in which a group of Northern California teenagers smoked marijuana every day at 4:20 p.m. Word of the ritual spread and expanded to a yearly event in various places. Soon, marijuana aficionados were using "420" as a code for smoking and using it as a sign-off on fliers for concerts where the drug would be plentiful.
In recent years, the April 20 events have become so widespread that several colleges have urged students to just say no. At the University of Colorado, Boulder, where thousands of students regularly use the day to light up in the quad, administrators sent an e-mail message this month pleading with students not to "participate in unlawful activity that debases the reputation of your university and degree."
A similar warning was sent to students at the University of California, Santa Cruz - home of the Grateful Dead archives - which banned overnight guests at residence halls leading up to April 20.
None of which, of course, is expected to discourage the dozens of parties - large and small - planned for Monday, including the top-secret crowning of Ms. High Times.
In San Francisco, meanwhile, where a city supervisor, Ross Mirkarimi, suggested last week that the city should consider getting into the medical marijuana business as a provider, big crowds are expected to turn out at places like Hippie Hill, a drum-happy glade in Golden Gate Park.
A cloud of pungent smoke is also expected to be thick at concerts like one planned at the Fillmore rock club, where the outspoken pro-marijuana hip-hop group Cypress Hill is expected to take the stage at 4:20 p.m.
"You can see twice the amount of smoke as you do at a regular show," said B-Real, a rapper in the group. "And it's a great fragrance."