Could legal marijuana become big business?

Does Tuesday's legalization of recreational pot use for adults in Washington State and Colorado signal a death knell for illegal marijuana across the United States -- and the start of a new, legal and profitable industry?

Supporters say the measures will generate tens of millions of dollars in revenue for state and local governments while undermining illegal drug enterprises.

"Prohibition has failed," said an editorial in the Seattle Times. "Licensing the growers and retailers will take marijuana out of the hands of criminal gangs and bring it into the open, where it can be regulated and taxed."

But just how to regulate and tax marijuana in those states remains a huge question, especially since the drug remains illegal under federal law.

Eighteen states and the District of Columbia have legalized the use of medical marijuana. Years of observations of the industry have given analysts a baseline for considering the financial and legal obstacles recreational pot stores will face.

"This is the tricky thing," says Dr. Alexandre Padilla, an economics professor at Metropolitan State University of Denver. "Already you have the issue with medical marijuana dispensaries -- where a lot of banks refuse owners of medical dispensaries to open accounts because they're afraid the feds will close their offices because they are violating federal law."

The U.S. Department of Justice has been relatively quiet on the issue, saying Wednesday it's reviewing the Colorado and Washington ballot initiatives, with "no additional comment at this time." But there are concerns that the measures could trigger legal challenges all the way up to the Supreme Court.

In Colorado, the first recreational pot stores are scheduled to open in January 2014. Local governments can still keep the stores out of their towns, and employers can prohibit their employees from using marijuana. The state "has a lot of work to do quickly in terms of setting up the appropriate rules and structures," Rosalie Pacula, with the Rand's Drug Policy Research Center, told the Denver Post.

Supporters of marijuana reforms say legalizing pot has potentially enormous financial benefits. They say pot is already one of the largest cash crops in the United States. And longtime observers believe that, if legalized and properly regulated, marijuana could become  a very cost-efficient commodity.

"It doesn't cost much to produce it if you don't have to hide it," said Bruce Benson, the chair of the economics department at Florida State University. "I don't know if there are the kinds of scale economies in marijuana production that that there are in beer production.  It's more of . . . a packaging thing for a retail market, a legal market. So you could see some substantial processing packaging plants perhaps develop. That's down the road."

But all of this is still speculative. "The voters have spoken, and we have to respect their will," Colorado Gov. John Hickenlooper, a Democrat who opposed the recreational marijuana measure in his state, said in a statement issued Tuesday night."This will be a complicated process, but we intend to follow through. That said, federal law still says marijuana is an illegal drug, so don't break out the Cheetos or goldfish too quickly."