The Global Marijuana March (GMM) is an annual rally held at different locations across the planet. It refers to cannabis-related events that occur on the first Saturday in May, or that weekend, or thereabouts. Marches, meetings, rallies, raves, concerts, festivals, info-tables, etc.. The home page is at GlobalMarijuanaMarch.org
The Global Marijuana March also goes by the name of the Million Marijuana March (MMM). It began in 1999. Over 562 different cities worldwide have participated since 1999. There are local names for the event too. Such as: World Cannabis Day, Cannabis Liberation Day, Global Space Odyssey, Ganja Day, J Day, etc..
The Global Marijuana March is a celebration embracing cannabis culture as a personal lifestyle choice. Participants unite to discuss, promote, entertain and educate both consumers and non-consumers alike.
One of the main organizers since 1999 is Dana Beal and his Cures-Not-Wars.org website. Another of the main organizers is CannabisCulture.com and its publication, Cannabis Culture Magazine. Both Dana Beal and CannabisCulture.com people have mailed thousands of GMM-MMM posters worldwide over the years.
The rally at Queen's Park in Toronto, Canada is a city tradition since 1999. 20,000 people showed up in 2007. 15,000 in 2008, despite the rain. For the May 2, 2009 event the Toronto Star reported: "Police estimate roughly 12,000 people filled the north lawns of Queen's Park yesterday afternoon, with about 5,000 participating in a 2 p.m. march to decriminalize marijuana."
In 1999 during the first worldwide Million Marijuana March New York City held another of its annual marijuana marches. The Village Voice reported on the police and organizer estimates of the crowd size: "the police claim it was 4000 people while organizers say 20,000".
Held in Regina on the first Saturday of May since 1999, originally at the Saskatchewan Legislature. Starting in 2001, it was held in Victoria Park, in the center of Regina's downtown, until 2008 when changes to the City's permit policy forced organizers to change the location to Central Park. The event features live music mixed with speakers on various topics, sometimes with only an incidental connection to marijuana. For example, 2007-2008 featured Jim Elliott from the Council Of Canadians, who primarily deal with issues surrounding Canada's independence from the U.S., and who used the Marc Emery case as an example of increasing U.S. interference. 
J-Day in Dunedin, New Zealand is celebrated in the city's centre of town, The Octagon, on the first Saturday of May (2nd, 2009) from 'High Noon' until 4:20 pm. Dunedin is arguably chronologically the first city in the world to host any GMM event. Named '4:20 Extreme', local participants climb the famous Baldwin Street to meet at the top by 4:20 am. Interestingly, locally J-Day coincides with The University of Otago Capping Parade, in which a multitude of ceremony-attending graduates parade down the main street on their way to the Town Hall ceremony, and also the University Hall Parade, in which University of Otago dormitory-student decorated themed floats parade down the main street, stopping in the Octagon typically armed with many water balloons, and collectively shouting chants of dormitory-specific pride.
Dunedin became famous for its JDay festivities in 2003 when around 50 activists marched to the Central Dunedin Police Station, where they planted cannabis plants and smoked cannabis in the main foyer as acts of protest. The event was given considerable national and international media attention as no arrests were made. The Central Dunedin Police Station was hot-boxed again on JDay in 2004 by over 100 activists, again with no arrests. This second incident was also covered by the media, resulting in the Dunedin Area Police Commander, Dave Campbell, justifying the fact that no arrests were made with the quote, "We had more important things to do" in the Otago Daily Times.
The 2007 International J-Day in Dunedin featured political speakers and music provided by local DJs and counted 170 people at mid-day. In the lead up to J-Day 2008, NORML NZ's Maryjane the Cannabus toured 42 towns between Auckland and Dunedin in 42 days for daily law reform rallies. The Cannabus arrived in Dunedin, New Zealand's most cannabis friendly city, on April 25 for a week long 'Cannabis Awareness Week' which was planned by Otago NORML and featured public workshops, informational lectures at Otago University, and a round-table discussion featuring university academics, MPs, and policy researchers. Cannabis Awareness Week culminated with J-Day on May 3, 2008.
The 2008 J-Day in Dunedin was well attended despite sleet and hail early in the day. Over 500 supporters participated in the event, enjoying games, prizes, political speeches and music from Bushmaster and Ashes of Eden.
The Dallas, Texas 2008 GMM more than doubled the 2007 attendance. Over 100 participants gathered from 12-1, and then marched from the Earle Cabell Federal Building down Commerce St., over to Dealey Plaza, where they protested on the Grassy Knoll, then over to the West End, crashing a Cinco de Mayo festival there. They then marched back over to the Federal Building. This was repeated at 3:00. The event was sponsored by DFW NORML and at the event, Barry Cooper (lecturer) announced his candidacy for the US Senate on a Pro-Decriminalization platform.
The Village Voice reported:
New York City's marijuana protest was one of 30 similar events held around the world on May 1. Speakers at a London rally, which drew more than 5000 people, railed against Giuliani's pot policies. One thousand protesters danced in the streets of Prague. Inmates at Ohio's Cuyahoga County Jail held up signs spelling W-E-E-D as 800 pro-pot marchers passed by. And at a 150-person rally in Winnipeg, Manitoba, the only arrests were of two drunks who were hassling the pot smokers.