The number “420,” as code for cannabis consumption, has been around since 1971, when — as one version of the creation story has it — five Northern California high school stoners coined it in reference to their daily, after-school toke-up time. That version of the story holds that in 1991, exactly 20 years later, members of the rock band the Grateful Dead gave 420 Day its first breath when they invoked it in a concert promotional flyer.

That makes today the 27th commemoration of the dope-smoker’s unofficial national holiday known as 420 Day.

But this is the first 420 Day since California voted decisively last fall to legalize marijuana for recreational use. (Medicinal use has been legal — and poorly regulated— since 1996.) And we’re still not any more convinced of the wisdom of legalization than we were last fall, when we urged a “no” vote on Proposition 64.

Kern County agreed with us wholeheartedly but most of the rest of the California — alas, as happens often — did not.

Two of our biggest concerns about decriminalization remain: Dealing with motorists who drive under the influence of marijuana, and coherently managing the often-sketchy cottage industry of marijuana dispensaries.

Colorado has seen an uptick in drugged driving since it legalized recreational pot five years ago, so California can expect to see the same, authorities say. Judging who’s too stoned to drive and who’s not can be a challenge, though, and law enforcement agencies throughout the state are racing to catch up.

The answer could be the Dräger 5000, a testing device now used by police in Los Angeles, New York, Arizona and Nevada, as well as in Australia, Belgium and Germany.

The permitting and monitoring of marijuana dispensaries is another issue that local authorities are scrambling to stay ahead of. Thus far, citing zoning restrictions, they’ve shut down a handful only to have others pop up elsewhere, Whack-a-Mole style.

It’s all evidence that, just as we declared back in October, jurisdictions throughout the state weren’t prepared for wholesale legalization.

And that doesn’t even factor in a host of other issues, such marijuana use as it relates to the workplace (just because it’s legal doesn’t mean employers can’t forbid it), health concerns associated with smoking and second-hand smoke (it’s as bad as tobacco), and the unsettled science of marijuana-steeped brain function (it can have lasting negative effects).

Sponsors needed 62 pages to set forth the details of Prop. 64 and they still managed to leave out a lot. Now it’s up to cities and counties to work those things out.

That doesn’t mean law-abiding pot smokers (that’s no longer an oxymoron here) shouldn’t enjoy themselves. It’s legal. Businesses and assorted celebrants around the state have planned parties, events and special promotions.

Take Oakland, where marijuana-infused candy manufacturer Kiva made 60,000 special-edition samples of the company’s low-dose Petra mints and was planning to hold 55 sampling events around the state this week. Or Tulare County, where workers at the area’s only dispensary, Canna Can Help, have ordered 1,000 tacos for a customer appreciation day.

Have fun — just use caution and show some regard for your nonsmoking fellow citizens. Merry 420 Day.

The number “420,” as code for cannabis consumption, has been around since 1971, when — as one version of the creation story has it — five Northern California high school stoners coined it in reference to their daily, after-school toke-up time. That version of the story holds that in 1991, exactly 20 years later, members of the rock band the Grateful Dead gave 420 Day its first breath when they invoked it in a concert promotional flier. That makes Thursday the 27th commemoration of the dope-smoker’s unofficial national holiday known as 420 Day.

However, this is the first 420 Day since California voted decisively last fall to legalize marijuana for recreational use. (Medicinal use has been legal — and poorly regulated— since 1996.) And we’re still not any more convinced of the wisdom of legalization than we were last fall, when we urged a “no” vote on Proposition 64.

Kern County agreed with us wholeheartedly but most of the rest of the California — alas, as happens often — did not.

Two of our biggest concerns about decriminalization remain: Dealing with motorists who drive under the influence of marijuana, and coherently managing the often-sketchy cottage industry of marijuana dispensaries.

Colorado has seen an uptick in drugged driving since it legalized recreational pot five years ago, so California can expect to see the same, authorities say. Judging who’s too stoned to drive and who’s not can be a challenge, though, and law enforcement agencies throughout the state are racing to catch up.

The answer could be the Dräger 5000, a testing device now used by police in Los Angeles, New York, Arizona and Nevada, as well as in Australia, Belgium and Germany.

The permitting and monitoring of marijuana dispensaries is another issue that local authorities are scrambling to stay ahead of. Thus far, citing zoning restrictions, they’ve shut down a handful only to have others pop up elsewhere, Whack-a-Mole style.

It’s all evidence that, just as we declared back in October, jurisdictions throughout the state weren’t prepared for wholesale legalization.

And that doesn’t even factor in a host of other issues, such marijuana use as it relates to the workplace (just because it’s legal doesn’t mean employers can’t forbid it), health concerns associated with smoking and second-hand smoke (it’s as bad as tobacco), and the unsettled science of marijuana-steeped brain function (it can have lasting negative effects).

Sponsors needed 62 pages to set forth the details of Prop. 64 and they still managed to leave out a lot. Now it’s up to cities and counties to work those things out.

That doesn’t mean law-abiding pot smokers (and, no, that’s no longer an oxymoron in California) shouldn’t enjoy themselves. It’s legal. Businesses and assorted celebrants throughout the state have planned parties, events and special promotions.

Take Oakland, where marijuana-infused candy manufacturer Kiva made 60,000 special-edition samples of the company’s low-dose Petra mints and was planning to hold 55 sampling events around the state this week. Or Tulare County, where workers at the area’s only dispensary, Canna Can Help, have ordered 1,000 tacos for a customer appreciation day.

Have fun — just use caution and show some regard for your nonsmoking fellow citizens. Merry 420 Day.