The medical marijuana shop next to a tattoo parlor on a busy street in Los Angeles looks much like hundreds of other pot dispensaries that dot the city.
Except for one thing: On the glass door - under a green cross signaling that cannabis can be bought there for medical purposes - is a sticker for the United Food and Commercial Workers union (UFCW), the nation's largest retail union.
The dispensary, the Venice Beach Care Center, is one of three medical marijuana dispensaries in Los Angeles that are staffed by dues-paying union members. Another 49 in the city plan to enter into labor agreements with the UFCW this year, the union says.
Together, the dispensaries are a symbol of the growing bond between the nascent medical marijuana industry and struggling labor unions.
During the last few years, unions, led by the UFCW, have played an increasingly significant role in campaigns to allow medical marijuana, now legal in California, 17 other states and Washington, D.C.
In the November elections, UFCW operatives also helped get-out-the-vote efforts in Colorado, where voters approved a measure that made possession of one ounce (28.3 grams) or less of the drug legal for anyone 21 and older. Washington state approved a similar measure and both states require regulation of marijuana growers, processors and retailers.
Union officials acknowledge that their support stems partly from the idea that the marijuana industry could create hundreds of thousands of members at a time when overall union membership is shrinking.
The U.S. Bureau of Labor Statistics reported last month that union members - who accounted for 11.8 percent of the workforce in 2011 - now make up about 11.3 percent of all American workers, the lowest percentage in nearly a century.
Retail unions such as the UFCW are fighting the rise of part-time workers and a steady drop in real wages over the last two generations. Organized labor also has been under pressure from Republican governors such as Wisconsin's Scott Walker, who led an effort to curb collective bargaining rights for public workers in that state.
Union officials say there are now 3,000 UFCW members who work in the cannabis industry, a tiny fraction of the union's 1.3 million members.
Industry advocates acknowledge that the legal marijuana industry's potential to produce jobs is difficult to project. One reason: uncertainty over how the U.S. government will deal with an industry whose product is illegal under federal law but increasingly accepted by state laws.
Since Colorado and Washington state voted to legalize marijuana on Nov. 6, President Barack Obama has said his administration will not pursue recreational pot users in those states.
However, the president has not said whether the U.S. government will allow widespread sales of the drug that would be legal under some state laws but not federal law.
Planning for a Boom
Despite such uncertainty, the marijuana industry's growth potential intrigues unions and retailers, among others.
An analysis by Sea Change Strategies, a research firm for non-profit organizations, estimated that the medical marijuana market could grow to $8.9 billion by 2016.
A study by Washington state's Office of Financial Management said legalization could result in $1 billion in sales per year in the state, which is home to about 2 percent of the U.S. population.
For people like Dan Rush, who leads the UFCW's cannabis division, the numbers hint at big things to come for the marijuana industry.
"Since Election Day, we've had a rush to join the union" in states where marijuana is sold legally, said Rush, who has become a key player in the union's efforts to promote the legal use of the drug. "I can't keep up," he said. "That's a direct result of the best poll in the world being Election Day."
Rush said that if the industry expands, as he and others hope, it would support jobs across the country, from growers to truck drivers to carpenters to retail clerks.
The scale of the business could rival that of a major U.S. crop or the alcohol industry, according to UFCW officials who estimate that 100,000 workers could be added to their union in California alone.
By joining a union, marijuana workers could have more sway in pressing for higher pay and benefits such as healthcare.
Unlike business owners in other industries who typically view unions warily, some legal marijuana retailers welcome the prospect of a unionized workforce - for now, at least.
Marijuana retailers have invited the UFCW into their shops. They think the union could give legitimacy to their business and support against competitors who, the retailers say, undercut the industry's standing by operating outside the law.
"It's the difference between being - I hate to use the term - but a street dealer and being a legitimate business operator," said Brennan Thicke, 38, one of the founders of the Venice Beach Care Center.
Resistance in Colorado
Other marijuana business owners aren't as enthusiastic about unions being involved with their enterprises.