2016 was a huge year for legal marijuana.

Four states — California, Massachusetts, Nevada, and Maine — all voted to fully legalize marijuana use, cultivation, distribution, and sales in the November 8 election. When the changes to the various state laws take effect, the number of states with fully legal cannabis will increase to eight (plus Washington, DC).

Though that's still a fraction of the US, California has an outsize impact; with nearly 40 million residents, it's the most populous state in the union. As a result, 21% of US citizens will soon live somewhere with access to fully legal marijuana.

More starkly: One in five people in the US will soon live somewhere with legal weed.

The states that have fully legalized marijuana are Colorado, Washington, Oregon, Alaska, California, Massachusetts, Maine, and Nevada. Those states and DC combined account for over 68 million Americans.

Marijuana-based products displayed at the Oregon's Finest medical-marijuana dispensary in Portland, Oregon, on April 8, 2014. REUTERS/Steve Dipaola

By far, the most impactful state to have full legalization is California. Voters there overwhelmingly chose yes to the ballot initiative to legalize marijuana, Proposition 64, in Tuesday's election.

Fifty-six percent of voters said yes to the initiative.

As of 12:01 a.m. on Wednesday, marijuana use was fully legal in California for those 21 and older. There's a $100 fine for smoking in public, and driving under the influence of marijuana remains illegal. California residents are allowed to grow up to six plants in their homes, and recreational sales from shops will become legal on January 1, 2018. The legislation is similar in the other three states that voted in favor of legalization last week.

The immediate implications for California's economy are expected to be huge.

New Frontier Data / Arcview Market Research

California is looking at $1.5 billion flooding into the marijuana market because of change in law, a number that is projected to swell to just shy of $3 billion in 2019 and nearly $4 billion by 2020, based on the latest report from New Frontier Data and ArcView Market Research.

The US's most populous state is already pulling in billions annually from medical marijuana, which was legalized in California by Proposition 215 back in 1996. The total size of the cannabis market there is expected to reach $4.27 billion in 2018 and then $6.45 billion by 2020, according to ArcView's projections.

Another question is what impact the presidential election will have on the ongoing push toward nationwide marijuana legalization. Though no one knows for sure, Bloomberg has an interesting look into how the legal marijuana industry is reacting.