The previous high for legalization topped out at 50 percent in 2011. That number slightly shrank to 48 percent in 2012.
Thirty-nine percent of people still oppose legalization.
A Gallup poll from earlier this year found 38 percent of people had tried the drug, largely unchanged from past years.
The only age group that opposes legalization by a majority is people over the age of 65. Only 43 percent of that group support legalization.
Support is highest among adults aged 18 to 29, with 67 percent of that group supporting legalization.
The survey comes after Washington and Colorado became the first two states to legalize the recreational use of the drug through ballot measures in 2012.
The Justice Department in August told both states it would not take action to have the laws overturned, while also maintaining it would not prioritize prosecution of recreational use.
White House spokesman Josh Earnest said at the time that low-scale prosecution of users is not the best use of resources, but that marijuana laws still serve a purpose.
"Having laws in place so these law enforcements resources can be targeted to drug kingpins and traffickers and others who contribute to violence on our streets is a very good use of those law enforcement resources," Earnest said.
While legal in Colorado and Washington, marijuana remains illegal on the federal level.
The poll surveyed 1,028 adults and has a 4 percent margin of error.