Just over half of Democrats and 55 percent of independents support legalization, but 2 in 3 Republicans oppose it.

Earlier this month, voters in Colorado and Washington both voted to legalize the drug for recreational use, the first time a state has done so. Voters in Massachusetts also approved the sale of medical marijuana.

Support for medical marijuana has skyrocketed, with 83 percent of those surveyed saying the practice should be allowed. That's up 21 points from a similar survey conducted in 1997. But despite widespread support for medical marijuana, more than half of voters say they think prescriptions for the drugs are not given for a "serious medical illness."

Voters also strongly believe the state governments should be in charge of determining the drug's legality. Marijuana remains illegal under national law, and there is the possibility that federal law enforcement will target marijuana sales in states where it was recently approved. The Obama administration has not yet said how it will address the legalization votes, but nearly 6 in 10 voters say the state governments should decide whether the drug is legal. Even 49 percent of those who oppose legalization say the decision should be left up to states.