Overall, 64 percent of Americans now support legalization, the highest percentage ever in Gallup polling.
“The trajectory of Americans' views on marijuana is similar to that of their views on same-sex marriage over the past couple of decades,” Gallup said in its analysis of the data. “On both issues, about a quarter supported legalization in the late 1990s, and today 64% favor each.”
Nationwide support for legalization first hit 50 percent in 2011, just ahead of historic votes in Colorado and Washington state to legalize recreational use of the drug in 2012. Since then, voters in six more states and the District of Columbia have approved recreational marijuana laws.
More than 20 percent of the U.S. population now lives in a state where marijuana use is fully legal, and even strong opponents of legalization concede that norms around marijuana use are shifting.
Meanwhile, many of opponents' fears about marijuana legalization don't appear to be panning out. States that have legalized pot are also beginning to reap some of the benefits of the policy change, including job growth, tax revenue and even some evidence of slowing in the opiate epidemic.
The sharp shift in Republican voters' views on pot is the most significant finding in the Gallup poll, coming during a time of increased federal skepticism of marijuana legalization efforts. Attorney General Jeff Sessions has asked lawmakers to undo federal protections for medical marijuana, repeatedly calling it a “dangerous drug.”
But greater support for legalization could complicate any administration efforts to crack down on pot. "Attorney General Jeff Sessions could find himself out of step with his own party if the current trends continue,” Gallup wrote.