The annual 4/20 pot-smoking rally, which drew crowds of up to 25,000 to the plaza of the Vancouver Art Gallery on Monday resulted in 64 people being treated in hospital, including teenagers, said health officials.

All the patients were treated at St. Paul's, making for a very busy night in the downtown hospital.

"64 people in the emergency department is a large number, in an already busy emergency department," said Dave Lefebvre, a spokesperson for Providence Health Care.

April 20, widely known in marijuana culture as "4/20," is a day when thousands of people gather for "smoke-ins" in cities across North America.

Thousands of Brazilians will celebrate 4/20 this week, but few could tell you why they’re coming out for pot at the end of April. There’s no 420 police code in Brazil, and like most other countries they write April 20th as 20/4 anyway. In fact, because of Mother’s Day and annual soccer championships, the date f 4/20 gets shuffled.

The first thing I notice about doing yoga stoned is my pulse. That otherwise inconspicuous sign of life is suddenly very much present, from my forehead to my pelvis, and the latter makes me want to giggle. I think it's okay to giggle, and so I do. Here inside this garage-turned-yoga studio in central Denver, everyone around me is making noises—giggles and more—upon taking her turn hitting the communal vape that's being passed around.

San Rafael High School’s claims to fame include adult actress Nikki Tyler and Night Ranger’s “Sister Christian” video, but the California campus is best known as the alleged birthplace of 420. Back in 1971, five classmates sought a hidden cannabis crop in the Point Reyes Peninsula, and 420 served as the code word for the search and their 4:20 p.m. meeting time. The legend may or may not be historically accurate, but 420 is definitely the preeminent counterculture holiday with annual cannabis celebrations on April 20. On the fifty shades of green scale, 420 ranks up there with St. Patty’s and Earth Day, and travelers can celebrate with cities to visit, things to do and places to munch.

Punta del Este, Uruguay

A majority of Americans support the legalization of recreational marijuana, according to a new poll from CBS News -- and it's the highest percentage in support since the news organization began asking the question in 1979.

Just in time for 4/20, the annual marijuana holiday, CBS News released a poll showing 53 percent of Americans are in favor of marijuana legalization.

At a Society for Human Resource Management conference in Washington DC last month, a session on drug testing in the workplace was so heavily attended that organizers had to switch rooms to accommodate the audience. Even then, it was standing room only. And the hour set aside for the talk wasn’t enough: outside the hall, employment attorney James Reidy, the presenter, answered questions for 40 minutes afterward.

Individuals looking to invest in the cannabis industry have multiple options to consider.

The two most popular routes are investing in producers, processors and retailers directly involved with the plant, or investing in ancillary businesses that provide services to the operators, including software companies, consulting firms and security providers.

Risk tolerance guides the investor’s path. For the risk averse, ancillary businesses can provide a safer investment free of potential hurdles put up by the federal government.

But for the risk seekers, obtaining licenses that allow cannabis production could be the most lucrative approach.