Following the passage of measures to legalize recreational marijuana in Oregon, Alaska and Washington, D.C., advocates say they are now focusing on California.

Oregon and Alaska voted to legalize recreational marijuana use on Tuesday. In Washington, D.C., residents voted to allow possession of marijuana, but not retail sales of the drug. Marijuana remains illegal under federal law. Oregon and Alaska will follow Colorado and Washington state, which legalized recreational use of marijuana in 2012.

Ethan Nadelmann, Executive Director of the Drug Policy Alliance, said it is likely pro-legalization measures will be on the ballot in 2016 in California, Maine and Nevada. They may also appear on the ballot in Massachusetts and Arizona, he said.

Because of California’s large population, a vote to legalize marijuana in the state would be “a real game-changer,” Beau Kilmer, Co-Director of the RAND Drug Policy Research Center, told The Wall Street Journal. There have been major changes since California voters defeated an initiative to legalize marijuana in 2010, Kilmer said. “There’s serious money behind these efforts and they’re spending more time putting the ballot initiatives together,” he noted.

Legalization opponent Kevin Sabet of Smart Approaches to Marijuana said voters will become more cautious in the future. “We are confident the more people know the truth about marijuana and the Big Tobacco-like marijuana industry, the more opposition to marijuana legalization will continue to grow,” he said.

Almost 55 percent of Oregon voters supported a measure to tax and regulate sales of recreational marijuana, while 52 percent of Alaska voters favored the state’s legalization measure.