Twelve years ago, mainstream politicians opposed marijuana legalization. Recreational use was forbidden even in the most liberal states.

Today, even conservative states are considering the policy — including North Dakota, South Dakota and Florida, through ballot initiatives this November. And both presidential contenders now favor legalization. Kamala Harris confirmed her support this month. Donald Trump says he will vote for Florida’s initiative. He also backs easing federal restrictions on weed. This is the first time even one major-party candidate has publicly supported legalizing pot.

The shift was unusually quick for American politics; it’s very rare for the bipartisan consensus to flip in less than a generation.

One reason politicians have changed their minds so quickly is that they are following a shift in voters’ views. In today’s newsletter, I’ll look at how public opinion evolved — and why Harris’s and Trump’s positions could matter even in states that have already legalized marijuana.

A quick shift

Americans’ views on domestic policy are largely stable. Consider guns: Congress passed the last major federal gun measure, the Brady Act, three decades ago. Since then, views on whether firearm laws should be made more or less strict have barely moved, according to Gallup. This is typical for most domestic policy issues, researchers have found.

Marijuana legalization is an exception. In 2000, 31 percent supported it; now 70 percent do.