A large national survey finds 52 percent of Americans favor marijuana legalization. The General Social Survey, conducted every two years, is widely considered to be the gold standard for public opinion research, according to The Washington Post.

The survey found 42 percent of respondents opposed legalization, while 7 percent were undecided. Support for legalization rose 9 percentage points from 2012. It is the first time the survey found a majority of Americans say they support legalization.

In 1974, 19 percent of those surveyed said they supported legalization. Support reached almost 30 percent in 1978, and then plunged to 16 percent in 1990. As states began to adopt medical marijuana laws, a growing number of people said they favored legalization.

Another recent survey found support for legalization differs by age and political affiliation. The Pew Research Center survey found among Republicans ages 18 to 34, almost two-thirds say they support marijuana legalization. Among Republicans ages 35 to 50, almost half approve legalization. The Pew survey found 77 percent of young adult Democrats and 61 percent of those ages 35 to 50, favor legalization.

Pew found 38 percent of Baby Boomer Republicans, ages 51 to 69, favor legalizing marijuana, compared with 66 percent of Democrats of the same age.

A survey conducted by Pew in 2014 found 75 percent of Americans think it is inevitable that recreational marijuana will become legal across the country. More Americans are in favor of overturning laws that require jail time for possessing small amounts of marijuana, the survey found. Fifty-four percent of respondents said they thought marijuana legalization would lead to more underage people trying the drug.

A Pew Research Center survey conducted in 2013 found 52 percent of Americans favor the legalization of marijuana.