About a thousand U.S. adults were surveyed for this study; of them 58 percent said marijuana should be made legal. That is an 8 percentage point swing from a 2011 poll.
Marijuana advocates consider this a potential tipping point in the fight to legalize pot.
Critics though say it's not a true reflection how Americans feel about getting high.
Marijuana supporters are seeing a shift in attitude when it comes to legalization. The drug is now legal in two states, Washington and Colorado.
Mason Tvert, communications director with the Marijuana Policy Project in Denver, said the big difference now is that more information is available about marijuana. He added that his group is pushing marijuana laws in 14 states, citing recent studies showing the drug isn't as harmful as once thought.
Dr. Mitch Rosenthal is founder of the rehab clinic organization Phoenix House. He said legalizing pot has a clear negative impact, especially on young people.
On the streets of New York, we found people's opinions were mixed.
Medical marijuana is currently legal in New Jersey. The marijuana policy project said it is also looking to pass similar legislation in New York.