Thousands sent up a cheer and smoked marijuana at the stroke of 420 p.m. on Wednesday in San Francisco's Golden Gate Park. They gathered at the park's "Hippie Hill" to toke up, eat and drink the afternoon away into the night. A plane dragging a banner encouraging attendees to "smoke weed" circled overhead, while unlicensed vendors set up tables and makeshift tents to sell all types and strains of bud, not to mention T-shirts, pipes and food. A group of Californian teenagers ritualistically smoked marijuana every day at 420 pm. The ritual spread, and soon 420 became code for smoking marijuana. Eventually 420 was converted into 420 for calendar purposes, and the day of celebration was born. This year's celebrations of all things marijuana throughout the U.S. came amid loosening restrictions and increasing tolerance for the plant's use from Alaska to Massachusetts. Here’s how people celebrated the marijuana day in United States
A woman smokes marijuana during the annual 4/20 marijuana gathering at Civic Center Park in downtown Denver, Wednesday, April 20, 2016. Public consumption remains illegal under the state's recreational pot law, which was passed in 2012. Fans of the drug have long marked April 20 as a day to enjoy pot — especially at 4:20 p.m. — and to call for increased legal access to it.
Corey Coka smokes marijuana during the annual 4/20 marijuana gathering at Civic Center Park in downtown Denver.
Destiny Sneed smokes marijuana during the annual 4/20 marijuana gathering at Civic Center Park in downtown Denver.
A gathered crowd smokes marijuana en masse - as per tradition at 4:20 p.m. - during the annual 4/20 marijuana gathering at Civic Center Park in downtown Denver.
Natalie Rice, left, kisses her new husband Lee Rice beneath a canopy of faux marijuana plants during a ceremony at the Cannabis Chapel, in Las Vegas. Natalie and Lee Rice were the first couple to marry at the marijuana themed wedding chapel, which opened Wednesday.
Shane Kinoshita from San Francisco smokes marijuana in Golden Gate Park in the area unofficially known as "Hippy Hill" in San Francisco. People descended on the park to smoke pot for the annual 4/20 celebration, in what may be the last year marijuana is illegal in California.
William Ealy from Richmond, Calif., smokes in Golden Gate Park in the area unofficially known as "Hippy Hill" in San Francisco.
Jade Seitz, from South Lake Tahoe, Calif., hula hoops in Golden Gate Park in the area unofficially known as "Hippy Hill" in San Francisco. In what may be the last year pot is illegal in California, thousands of people are expected to converge on San Francisco's Golden Gate Park Wednesday for the annual 4/20 marijuana holiday.
Donovan Tryon inspects marijuana while shopping at Blum in Las Vegas. Wednesday was the opening day of the marijuana dispensary.
People smoke marijuana during the "420 Toronto" rally in Toronto. Cannabis possession is illegal in most countries under a 1925 treaty called the International Opium Convention. But just like the U.S., some nations either flout the treaty or don't enforce it. Legalization supporters consider pot possession either legal or tolerated in Argentina, Bangladesh, Cambodia, Canada, Chile, Colombia, the Czech Republic, India, Jamaica, Jordan, Mexico, Portugal, Spain, Uruguay, Germany and the Netherlands.