Happy 4/20! For those of you who don’t know, that number is code for cannabis, and users are celebrating worldwide.

Recreational use of marijuana is legal in four states and Washington, D.C., but not New York. While pot arrests have declined significantly in NYC because of more lenient policies by the NYPD under Mayor Bill de Blasio, it is still against the law to smoke weed here.

Meanwhile, New York recently legalized the use of medical marijuana, but only under stringent conditions — some say too stringent. Count my brother, Bob Vogel, among them.

Bob has spinal stenosis, the same condition afflicting Mets third baseman David Wright. Muscular dystrophy and rheumatoid arthritis are among the ailments not considered serious enough for medical marijuana relief in this state, while spinal stenosis sufferers must jump through hoops to get help. Bob has tried many medications and acupuncture, to no avail. “I’m not looking to get high, just for pain relief,” he told me. “Why can’t I go to my doctor and get a prescription for it like any other drug?”

Good question. Your doctor can still prescribe highly addictive pain killers, but probably not marijuana for medicinal use. There are just 455 doctors registered for the state’s medical pot program.

Supposedly one of the more progressive states in the nation, New York’s attitude toward the legalization of pot and particularly the use of medical marijuana is anything but. State Sen. Diane Savino (D-Staten Island) recently introduced four bills to expand the program.

In a 2015 Gallup poll, 58 percent of Americans favored legalizing pot (it was 12 percent in 1969, when Gallup first asked the question). At least 20 states have recreational marijuana legalization on the ballot in 2016. Not New York.

This will change in the near future. Why? Follow the money. Just like state- sponsored gambling, pot brings in huge revenues to states where it’s legal, and New York lawmakers won’t be able to resist this cash cow much longer.

When? Perhaps by the next time 4/20 rolls around. Meanwhile, the state’s draconian medical marijuana program should be rewritten to be more realistic and humane — now.

Playwright Mike Vogel blogs at newyorkgritty.net.