Proponents argued that it's important to be able to control, regulate and tax marijuana. California's nonpartisan Legislative Analyst's Office estimated the state could collect up to $1 billion in taxes a year.
Opponents were worried about safety, citing problems in other states that have legalized recreational marijuana.
Voters led the way in the U.S. when they approved medicinal marijuana in California in 1996.
When will it take effect?
Adult use sales of marijuana will begin Jan. 1, 2018, but consuming marijuana became legal as of 12:01 a.m. Wednesday.
What will the restrictions for recreational marijuana?
In general, the proposals for recreational pot would treat cannabis similar to alcohol. Consumption would be limited to people 21 or older and forbidden in most public spaces. Pot would be highly regulated and heavily taxed.
Where is recreational marijuana already legal?
Alaska, Colorado, Oregon, Washington state and the District of Columbia. If California votes "yes," recreational cannabis would be legal along the entire West Coast, giving the legalization movement powerful momentum. That could spark similar efforts in other states and put pressure on federal authorities to ease longstanding rules that classify marijuana as a dangerously addictive drug with no medical benefits.
How much marijuana can you have?
Proposition 64 would allow California residents 21 and older to legally possess up to an ounce of weed and grow six marijuana plants at home.
Because marijuana is now legalized in California, convicted felons have a chance to have their record expunged if the crimes they committed involved things that are now legal.
The Associated Press contributed to this report.
Learn more about Proposition 64 with these videos from SeePolitical.