DENVER >> Thousands of people are expected to join an unofficial counterculture holiday celebrating marijuana in Colorado and Washington this coming weekend, including out-of staters and even packaged tours. The events and crowds will test the limits of new laws permitting pot use by adults.

More than 50,000 are expected to light up outdoors in Denver’s Civic Center Park on April 20 to celebrate marijuana legalization. Thousands more are headed here for the nation’s first open-to-all Cannabis Cup, April 20-21, a domestic version of an annual marijuana contest and celebration in Amsterdam. Expected guests at the Cannabis Cup, a ticketed event taking place inside the Denver Convention Center, include Snoop Lion, the new reggae- and marijuana-loving persona for the rapper better known as Snoop Dogg.

Marijuana activists from New York to San Francisco consider April 20 a day to celebrate the drug and push for broader legalization. The origins of the number “420” as a code for pot are murky, but the drug’s users have for decades marked the date 4/20 as a day to use pot together.

Marijuana remains illegal under federal law, and its sale without a doctor’s recommendation isn’t allowed yet in Colorado or Washington. Neither state allows open and public use of the drug. But authorities largely look the other way at public pot-smoking, especially at festivals and concerts, and entrepreneurs are finding creative ways to capitalize on new marijuana laws.

One of them is Matt Brown, co-owner of Denver’s new “My 420 Tours,” which gives traveling pot users everything but the drug. Brown has sold 160 tour packages to visiting pot smokers for the April 20 weekend. Prices start at $499, not including hotel or air.

The tour sends cannabis tour guides to pick up marijuana tourists at the airport in limousines, escort them to Cannabis Cup and other Denver-area marijuana celebrations and deposit them at a hotel where smoking — tobacco or reefer — is permitted on room patios.

Marijuana tourists on Brown’s tour can add extra days of touring medical marijuana dispensaries and commercial growing operations. A cannabis cooking class is another option. Five-day tours run $649 to $849.

Brown, a medical marijuana patient who is new to the travel business, says his tours will enable sharing of pot but not selling it. Eighty percent of his clients are coming from outside Colorado — meaning it’s illegal for them to bring marijuana from home. And because commercial pot sales in Colorado don’t start until January, out-of-state visitors can’t yet buy pot at Colorado’s 500-plus dispensaries.

Despite the legal barriers, Brown said his tours quickly filled to capacity and he had to turn away would-be cannabis tourists. He’s hoping to book future pot-themed weekends if the April 20n weekend does well.

“People are fascinated by what’s happening here, and they want to see it up close,” Brown said. “We want to make sure people don’t come here, land at the airport, rent a car and drive around stoned all weekend.”

The tour group isn’t affiliated with the Cannabis Cup, sponsored by High Times Magazine, which has run similar events for medical marijuana in nine cities. The magazine’s editorial director, Dan Skye, says this month’s U.S. Cannabis Cup was timed for the April 20 weekend.

“4/20 is the national stoner holiday, for lack of a better word,” Skye said. “It gets bigger every year, and this year, after the legalization votes, it’s going to be absolutely huge.”

The magazine planned to award Snoop Lion with a “lifetime achievement” award at a Denver ceremony Friday. A Cypress Hill/Slightly Stoopid concert was planned Saturday at the iconic Red Rocks Amphitheater just west of Denver. Both events sold out weeks ago.

A few dozen miles northwest of Denver, the University of Colorado in Boulder will try to dampen pot celebrations on April 20. The campus once held the nation’s largest college 4/20 celebration, drawing an estimated 10,000 in 2010. The legendary smokeout was cited by Playboy magazine when it named Colorado the nation’s top party school in 2011 .

After the Playboy mention, the university stepped up efforts to shut the celebration down. Campus officials last year roped off the site of the smokeout, Norlin Quadrangle, reducing the 4/20 crowd to a few hundred protesters. The school planned another shutdown Saturday.

Celebrations were planned in Washington state, too, though April 20 isn’t as broadly celebrated as Seattle’s annual Hempfest, which draws hundreds of thousands of people to a waterfront park every summer.

The April 20 celebrations in Washington included a Seattle party being put on by DOPE Magazine at an artist work space and studio. About 1,500 were expected for glassblowing demonstrations, music, dancing and a bar where revelers can vaporize their pot, plus the judging for the “DOPE Cup” — an award for the best bud. There will be a smoking tent set up outside, along with food trucks to combat any cases of the munchies.

“It’s pretty monumental,” said DOPE editor in chief James Zachodni. “This is the first time in the U.S. there’s been a cannabis holiday with a legal aspect to it.”

Back in Colorado, longtime pot user Andrew Poarch says this year’s April 20 observations in Colorado have taken on epic significance. He’s joining dozens of friends to hire a bus from Colorado Springs to attend Denver’s Cannabis Cup.

“It’s going to be a lot bigger, a lot more people,” he predicted. “People are trying to outdo themselves because it’s a party and a celebration. We beat prohibition. It’s a pretty big deal.”

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