Massachusetts likely voters are in favor of legalizing marijuana for people 21 and older, with 55 percent saying "yes" to Question 4, according to a new poll from WBUR/MassINC Polling Group.

Forty percent said they would vote "no" if the election on the November statewide ballot measure was held today. Five percent said they didn't know how they'd vote or they were undecided.

Question 4 seeks to set up a regulatory structure for the taxation of commercial marijuana, under a proposed Cannabis Control Commission, a framework that proponents say will drive down the black market. Opponents have been urging voters to reject the measure, saying marijuana is a potent gateway drug to harder substances.

Voters could legalize recreational marijuana in five states this November and medical marijuana in three more. This record number of state ballot measures promise to be a great boon for the cannabusiness industry. With national prohibitions against interstate cannabis commerce, as well as current federal banking and drug laws, large companies have been kept out of the industry, so the market is still primarily comprised of small businesses.

California, Arizona, Maine, Massachusetts and Nevada will consider legalizing  the recreational use of cannabis while Florida, Arkansas and North Dakota will decide on marijuana for medical purposes.

What’s going on state by state?

California, Prop 64 

Opponents of legalizing marijuana in Massachusetts are launching their first television advertisement Tuesday, a powerful 30-second spot that imagines an almost dystopian neighborhood overrun by pot shops and stoners.

In the ad, a mother drives her daughter through a familiar suburban scene of strip malls, passing one marijuana store after another, signs alighted with green cannabis leaves.

“Question 4 would allow thousands of pot shops and marijuana operators throughout Massachusetts — in neighborhoods like yours,” a female narrator says, referring to the Nov. 8 ballot measure.

No matter who wins on Election Day, cannabis will have a big day at the ballot box.

Five states — Arizona, California, Maine, Massachusetts and Nevada — have initiatives to legalize marijuana for adult recreational use. Four states — Arkansas, Florida, Montana and North Dakota — have proposed legalizing marijuana for medical purposes. All of the recreational use initiatives are currently ahead in the polls.

The campaign working to block marijuana legalization in Massachusetts on Thursday urged voters to consider the effect legal pot would have on the state's roadways, saying Question 4 "will result in more tragic traffic deaths on our roads."

The Campaign for a Safe and Healthy Massachusetts on Thursday levied an attack against Yes on 4, the group promoting legalization, charging the group with deceiving voters on the traffic safety implications of Question 4.

"Instead of deceiving voters and attacking facts, the Yes on 4 campaign should come clean and admit what is plainly obvious -- that passing Question 4 will result in more tragic traffic deaths on our roads," Nick Bayer, campaign manager for Safe and Healthy Massachusetts, said in a statement.

A review last week by the Washington Post shows a statistically insignificant majority in favor of legalizing so-called “recreational” marijuana in the five states that will be voting on it on election day: California, Massachusetts, Nevada, Maine, Arizona. The five states were obviously specifically selected by the pot lobby as the next to join the Portlandia states of Oregon and Washington, as well as libertarian Alaska, and the new spring-break destination Colorado as the only states to completely decriminalize marijuana.

A long conversation with the renowned travel guide on his campaign to legalize marijuana.

Rick Steves is better known to living rooms across the United States for his tranquil guides to Europe. However, in his free time from his professional job, Steves has another passionate pursuit: Legalizing marijuana.

The 60-year-old travel writer, TV personality—and occasional pot smoker—has been a longtime advocate of drug policy reform in the United States, to the chagrin of some of his show’s viewers.

A dozen medicinal cannabis cultivators and processors have partnered with Medicinal Genomics to record and track the genetics of cannabis strains on the Bitcoin blockchain to ensure product consistency and quality.

As many as five states could approve its recreational use this November, potentially signaling a point of no return for legalized pot.

Recreational marijuana users can now legally light up a joint in states representing about 5 percent of the U.S. population. By the time Americans wake up on November 9, that percentage could be swelling to more than one-quarter.

Voters in five states – Arizona, California, Maine, Massachusetts, and Nevada – will decide this November on ballot initiatives seeking to legalize and regulate the adult use, production, and retail sale of marijuana. Polling data shows these measures to be leading among likely voters.