With marijuana now legal in some form in 28 states and Washington, D.C., it is evident that Americans are rethinking the drug’s place in society.

Support for marijuana legalization has grown steadily in the past 25 years, from about 20 percent in 1990, according to public opinion surveys, to 57 percent in the latest Pew Research survey released in October 2016.

University of Nebraska-Lincoln sociologist Philip Schwadel dug into more than 40 years of data to determine how the tide turned in marijuana’s favor. In a forthcoming study, he refutes the popular conception that younger generations have shifted the needle of public opinion by embracing more socially liberal policies. Instead, he found, the legalization of marijuana has seen support grow across all demographics.

“Clearly, some people have changed their minds on this subject,” said Schwadel, a professor of sociology at Nebraska. “If you think about how rapidly the change in support happened, it’s not that surprising. Not enough older cohorts have died off and fewer cohorts have come into existence for this much change to occur.”

The study, which used data from the General Social Surveys taken from 1973 to 2014, employed a new analysis technique designed to separate changes across birth cohorts or generations from changes across time periods, which allowed Schwadel to demonstrate the lack of generational effect.

Besides looking at whether the shift in support was generational or across society as a whole, Schwadel also examined changes in different demographic groups. This produced some surprises, too, Schwadel said.

For example, support for legalization increased among both African-Americans and whites, but it grew more rapidly among Caucasians.

“If you go back to the 1970s, African-Americans were more likely than white Americans to support legalization, and today, it’s basically flipped from African-Americans being moderately more supportive of legalization to whites being moderately more supportive,” Schwadel said.

The demographic breakdown also revealed a widening gap between Republicans and Democrats on the issue. Survey data from the 1970s, 1980s and 1990s showed only a slight difference in support — about a fifth of Republicans supported legalization, while a larger quarter of Democrats supported it.

The chasm widened over the next two decades, and the 2014 data showed about 40 percent of Republicans supported legalization and 59 percent of Democrats support it. Another gap closed: In the 1970s, there was a large difference in support for legalization between high school and college-educated Americans. By 2014, there was no discernible difference between the groups. Still, Schwadel said, adults with less than a high school education are less likely than high school and college-educated Americans to support legalization.

Schwadel said more research is needed about pro-legalization attitudes, especially determining what kind of legalization is actually supported, as well as investigating why Americans seem more ready to make marijuana available.

“Research has suggested that Americans are becoming fed up with the war on drugs, especially the war on marijuana, but it’s important to understand what the growing support for legalization in public polling actually means for making policy,” he said.

The study, which was co-authored by Christopher Ellison of the University of Texas at San Antonio, is in an upcoming issue of The Sociological Quarterly.

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