NYC kicks off annual 4/20 marijuana celebration with vendors selling weed in Washington Square Park

The annual 4/20 celebration of cannabis is under away across the US.

In Washington Square Park in New York - a popular spot among smokers year-round - gatherings were larger and aromas were richer than usual. 

This year's celebration marks a major triumph for the plant's devotees - who for the first time are able to buy weed from some of the city's first licensed dispensaries.

As reggae music sounded, vendors set up tables to sell the cannabis flower, pre-rolled joints and edible THC products. Also on sale were budding cannabis seedlings, ready to be taken home and eventually cultivated into flowering plants. 

One man was equipped with hand-held 'cloud cannon', which he used to dowse willing attendants in plumes of marijuana smoke.

Celebrations are expected to reach a crescendo at the symbolic time of 4:20pm - meaning the West Coast is still a few hours away from getting 'lit.' 

On April 20 in Washington Square Park in New York, gatherings were larger and aromas were richer than usual. An elated man is pictured sitting behind a plastic table, basking in the sun, holding up a joint, and selling his wares

A woman in Washington Square Park enjoys a joint in the sun in the run up to 4.20pm on 4/20

People were selling the cannabis flower as well as small plants which could be taken home and cultivated

On Thursday afternoon Washington Square Park started to fill with people celebrating 4/20

Two people pose for a selfie in Washington Square Park on Thursday afternoon, each equipped with a joint

The origins of '4/20' as an internationally observed weed holiday are generally unknown.

In recent years, though, a consensus has emerged around the most credible explanation: that it was started in the 1970s by a group of students at San Rafael High School in California, who would meet each day after lessons at 4.20pm and smoke a joint.

The term then became associated with cannabis more generally, and eventually 4/20 was translated into April 20. Since the day is observed around the world - in countries where weed is both legal and illegal - celebrations vary.

In some places its an opportunity for disgruntled smokers to protest laws criminalizing the plant, in others it's a celebration among its fans that the plant even exists. 

On the other side of New York City, the group Black Girls Smoke is hosting its third annual 'Puff in the Park' event in Prospect Park in Brooklyn. Weed is now legal in New York - but smoking in the city's parks in forbidden, although that rule is widely-flouted. 

Black Girls Smoke is a cannabis community that seeks to break down stigmas and gender biases that prevent black women from getting high.

'We would like to see a designated cannabis smoking area in the park,' its founder Vic Styles told NBC New York. 

Congregation of weed smokers gather in the sun in Washington Square Park in observance of 4/20 

A man dressed in a fitting hoodie exhales smoke as he smokes a joint in Washington Square Park on Thursday afternoon

Different vendors sold different varieties of cannabis on folding tables around the Washington Square Park fountain

A group made the most of the good weather by settling down on a picnic blanket to smoke weed

In true communal spirit one vendor assists a man in taking a hit from a bong in a busy Washington Square Park on Thursday afternoon 

Washington Square Park in Manhattan is known for being a popular site among weed smokers but on 4/20 they show up in full force

A couple are pictured enjoying both the sun and a joint, just like many of the other weed-enthusiasts who showed up to Washington Square Park on Thursday

Hippie Hill in San Francisco's Golden Gate Park is expecting to draw 20,000 visitors - usually the largest event in the state, according to KTVU.

It's the second year that onsite cannabis sales are legal at the event.

For security measures around 100 security guards will patrol the hill. There will also be 163 portable toilets, extra parking patrol officers, and a cleanup crew.

'It's a beautiful day,' Jakar Lowe of Redwood City told the station. 'Weather really plays a factor. I came out early and if there are any clouds, I plan to blow some smoke their way to clear them out.'

In Seattle, one movie theater is offering a 'dank double feature,' with Cheech and Chong's 'Up In Smoke' paired with the 1930s cult classic 'Assassin of Youth'.

In Boston, a pottery party is offering participants a chance to make their own pipe.

In Kansas City, Missouri, heavyweight boxing legend Mike Tyson and wrestler Ric Flair were preparing to attend the Smokey Rivers 420 Fest, where Wiz Khalifa will be headlining.

Smokers that weren't into the idea of having to roll their own joints had the option of buying them pre-rolled

Technology has revolutionized marijuana consumption. A woman in Washington Square Park is pictured selling electronic weed vapes

Three men confer in front of a stand selling cannabis beside the Washington Square Park fountain 

In Missouri the recreational sale of cannabis was launched in February.

In February medical marijuana was legal in the state since a ballot measure passed in 2018, but voters went a step further in November by approving a constitutional amendment legalizing the drug for anyone 21 or older.

Last November an amendment was passed making non-medicinal pot legal in the state in December, but sales were stalled because the health department needed to issue business licenses.

Tyson is in Missouri is promoting his brand, Tyson 2.0, as part of a wider tour of several states.

Recently Tyson 2.0 introduced Mike Bites, cannabis edibles in the shape of an ear with a bite mark - an homage to Tyson's historic 1997 fight against Evander Holyfield in which he bit off a chunk of his opponent's ear.

The product propelled his brand to new heights, taking advantage of loosening cannabis laws around the county. 

'They're sold out, you can't find any,' Tyson said in an interview with Cannabis & Tech Today regarding Mike Bites. 

Cannabis is know tolerated for recreational use in 38 states - most recently Kentucky last month.