The cannabis industry also took stock of the massive market California represents, while police agencies, prosecutors, state regulators and tax collectors took steps on the day after the election to accommodate the new law.
Proposition 64, which allows California adults to possess, transport and buy up to an ounce of marijuana, won passage with 56% of the vote.
Similar ballot measures were also approved Tuesday in Massachusetts and Nevada, and one is ahead in Maine, although that one may face a recount. Arizona was the only state to reject an initiative that would have allowed possession of recreational marijuana. Florida, North Dakota and Arkansas approved medical marijuana initiatives.
"It was really a remarkable set of victories last night," said Ethan Nadelmann, executive director of the Drug Policy Alliance, in a conference call with reporters. "There is a massive sense of momentum in this regard."
Recreational use had been approved in previous years in Alaska, Oregon, Washington and Colorado.
Lynne Lyman, California state director for the group, noted that 40 million people now have access to legal recreational marijuana.
"We did something really significant last night in California," she said.
Kevin Sabet, president of the opposition group Smart Approaches to Marijuana Action, said it was no surprise that "deep-pocketed pro-marijuana investors prevailed in California."
But he held out hope that the new Trump administration would change federal policies that have encouraged states to adopt legalization laws.
"We're really in a whole new unknown world here," Sabet said.
Trump said during the campaign that he would respect states that adopt their own marijuana laws, but some in his inner circle, including former New York Mayor Rudy Giuliani, have pushed for tough enforcement of drug laws in the past, Nadelmann said. One concern is that Trump might make Giuliani attorney general, which oversees drug enforcement, the activists said.
"What gives me real concern is the election of Donald Trump," he added. "Donald Trump is totally unpredictable on this issue."
California Lt. Gov.
"I don't see any issues if the president-elect is consistent with his rhetoric from the campaign trail that established a framework of supporting states' rights," Newsom told reporters Wednesday.
One issue supporters think might pressure the federal government to ease restrictions on marijuana is its potential economic value and the taxes it would produce.
A new study released Wednesday found the increase in the country's marijuana market with California on board is staggering, compared to the next largest market in Washington state.
The smaller state is expected to have total sales of medical and non-medical marijuana of more than $2 billion by 2020, according to a study by New Frontier Data, a data analytics group, in partnership with Arcview Market Research.
In comparison, California's market is expected to reach $7.6 billion by 2020, according to the study.
The growth of markets in states that previously approved marijuana was strong, said Troy Dayton, chief executive of Arcview Group. "Now with these decisive ballot victories for legalization, growth will be off the charts," he said.
Wednesday also saw a flurry of activity by state and local agencies that have to implement aspects of the new Adult Use of Marijuana Act.
The Los Angeles County district attorney's office issued a 14-page memo to its prosecutors outlining the new ways it will handle marijuana cases as well as filings by those who want convictions for marijuana cleared from their records.
The ballot measure means numerous marijuana offenses have been decriminalized or reclassified, according to Chief Deputy Dist. Atty. John K. Spillane.
"As a result, pending felony cases where all the charges have been reduced to misdemeanors will be transferred to the appropriate city prosecutor's office unless the office regularly handles the misdemeanors for that area," he wrote to his field attorneys.
In addition, the California Highway Patrol has launched expanded training of its field officers on how to identify when a motorist using marijuana is impaired, Assistant Chief Omar Watson said Wednesday.
"The main thing we are going to do now that the law has passed is to really look at our training, to make sure our officers can more acutely know what the objective symptoms are when it comes to someone who may be under the influence of marijuana," Watson said.
He also said a public education campaign will be launched against drugged driving.
The Los Angeles County Sheriffs' Department also plans to educate its deputies about how the new law affects the handling of drug cases, according to Capt. Jeffrey Scroggin.
He noted that the ballot measure immediately legalizes possession of an ounce of marijuana for recreational use, but it cannot legally be sold until the state begins licensing pot shops — and the state has until Jan. 1, 2018, to begin issuing permits.
A newly named Bureau of Marijuana Control has already begun developing regulations for deciding how to issue licenses for medical marijuana dispensaries and will expand to include pot shops selling recreational marijuana, according to Lori Ajax, head of the agency.
"Although meeting the Jan. 1, 2018, implementation date will be challenging, we have already made great progress with medical cannabis regulations that will help us reach this new goal," Ajax said Wednesday.
State lawmakers said they are already working on the possibility of allowing interim sales licenses for medical marijuana dispensaries until the new state licenses are issued.
The state also needs to find a system for handling the hundreds of millions of dollars generated by the marijuana industry in California given that federally regulated banks will not accept drug proceeds, said
In addition to pot shops having difficulty handling their profits, the state faces a burden accepting up to $1 billion in annual taxes in cash.
"We are going to have to figure out the cash issue and how we are going to accept the cash," Ma said.
One idea is to have a tax official stationed at branches of Bank of America, which handles tax proceeds, so the official can accept cash payment of taxes and then deposit the money as state revenue.
The results of a handful of other ballot measures were not called until early Wednesday, when the Associated Press determined voters had approved a $9-billion school construction bond, but rejected three other measures: Proposition 60, which would have required the use of condoms in adult films; Proposition 62, a repeal of the death penalty; and Proposition 61, a prescription drug pricing measure fiercely opposed by the pharmaceutical industry.
Los Angeles Times staff writer Christine Mai-Duc contributed to this report.