Armed security personnel scan the crowd from a 20-foot-tall platform during the 4/20 Rally at the Civic Center in Denver, Colorado, April 20, 2014. REUTERS/Mark Leffingwell An estimated 80,000 people packed into Denver's main square on Easter Sunday for what was billed as the "biggest marijuana rally in history".

The annual event celebrating "world weed day" was the first since Colorado began selling the drug for recreational use in licensed shops on Jan 1.

In America's first cannabis-legal state it is still not permitted to smoke the drug in public spaces outdoors.

But many the crowd ignored signs to that effect and a thick fog of cannabis fumes rose over Civic Center Park next to the Colorado state capitol. Armed security was present but largely ignored infringements.

Police said a total of 130 people were arrested or issued on-the-spot fines. Of those, 92 were for public consumption of cannabis and 22 people "went to jail".

Tourists had flooded into Colorado for the event and 20 of those either arrested or fined were from outside Colorado. The fines were $150.

Denver Police spokesman Sonny Jackson said officers had avoided wading into the crowd but "those ticketed were blatantly in violation of state law and city ordinances" regarding outdoor smoking.

Paramedics treated 14 people and half a dozen were taken to the emergency room of Denver Health Medical Center after passing out.

At 4.20pm large sections of the crowd lit up simultaneously as police stood by. The number 420 has become symbolic for pro-cannabis campaigners, the significance appearing to have originated with a group of California teenagers who would meet at 4.20pm to smoke cannabis.

Not everyone at the rally was taking the drug. Dennis Miller, 55, a contractor, and his wife Teresa, 49, were there with their 19-year-old daughter and abstained.

Mr Miller said: "Our daughter wanted to come so we're just hanging out. The way I see it young people are going to do it anyhow so if you make it legal at least it's regulated."

Mrs Miller said: "There's so many age groups and walks of life together in one place here. I think people are getting more open to it."

Gabor Szekely, 24 an engineering student at the University of Colorado, brought his mother Eva Ovari, 52, who was visiting from Belgium.

He said: "I think the other American states will follow, it's just question of time. It's absolutely the right way to go."

But his mother said: "I've never seen anything like this. I've never tried marijuana before and I'm not going to try it today. I don't think it will happen in Belgium. It's a different mentality."

The crowd included many people in wheelchairs like Marnee Moralez, 50, who suffers from severe arthritis.

Lighting up a joint, she said: "The arthritis is really bad, it's in my bones. But marijuana takes the pain away, sometimes I can even stand up.

And it makes you happy. What's wrong with that?" She was being looked after by her son Shawn, 25, a US Air Force veteran who fractured his back on the flight line.

He said: "It helps me with the pain and also anxiety. It's wonderful. There's a whole bunch of us veterans across the country and I think if we featured more in the debate there would be more respect for legalization."

Herb Cross, 53, a truck driver from Redding, California, said other states should follow Colorado in allowing the use of cannabidiol, a cannabis compound, to treat children suffering from seizures.

He said: "My daughter suffered from epilepsy and she passed about 10 years ago. I think it might have helped a lot. It may have saved her if it had been available.

"I really hope California will legalize. It just costs so much to enforce the law and lock up people for having a bit of marijuana on them. There are so many prisoners in jail that are costing us a lot of money."

In Canada there were pro-legalisation rallies across the country. More than 2,000 people gathered on the lawn on Parliament Hill in Ottawa, and there were also rallies in Vancouver and Toronto.