The poll conducted by CNN and ORC International and released Monday indicates 55 percent of respondents said the drug should be legalized; 44 percent said it should not.
The findings, CNN said, mirror a Gallup poll released in October that showed similar rates of response in favor of legalizing pot.
The poll is the first conducted on the issue in 2014, when Colorado became the first state in the country to legalize the drug for recreational use and regulate its sale. Washington state will do the same later this year. Voter referendums in the states passed in 2012.
Still, there exist deep divides on the issue, pollsters said. People ages 18 to 34 are far more likely than older Americans to support legalization. Two-thirds of young people in the poll supported it. The rate of support drops to 39 percent -- or almost two-thirds opposed -- among Americans 65 or older.
Two other groups, Southerners and self-identified Republicans, are the only other groups significantly opposed to legalization, the poll found.
"Clearly there are some reservations about marijuana, but not the widespread fear that existed during the original War on Drugs in the 1970s," CNN polling director Keating Holland said.
The poll was conducted Jan. 3-5, surveying 1,010 Americans. Its margin of error is 3 percentage points.