Joe Amon, The Denver PostA cloud of smoke covers the crowd at 4:20 p.m. at the Annual Denver 4/20 Rally in Civic Center Park, April 20, 2010.
Kathryn Scott, The Denver PostKristen Aaland dons her event glasses as thousands gather at Civic Center Park in Denver for the annual 4/20 Pot Rally where hip-hop music blared from the stage and the crowd all light joints and pipes at exactly 4:20 p.m. The 420 rally is an annual event held throughout the country on April 20.
Mark Leffingwell, Daily CameraGarrett Kramer smokes marijuana during the 4/20 event on Norlin Quad at the University of Colorado in Boulder, Colo., Tuesday, April 20, 2010. Advocates from New Hampshire to California trumpeted marijuana's rising commercial and political acceptance while producing collective clouds of pungent smoke _ often under the watchful eyes of law enforcement officers who for the most part let the parties proceed.
Mark Leffingwell, Daily CameraMembers of the Boulder Police Department and University of Colorado Police Department wander through the crowd during the 4/20 event on Norlin Quad at the University of Colorado in Boulder, Colorado April 20, 2010.
Joe Amon, The Denver PostHeadache and Kevin pistol of Hustlinflow.com rap during the Annual Denver 4/20 Rally in Civic Center Park.
Hyoung Chang, The Denver PostMalia Knapp of Denver, center, is celebrating at the Denver 4/20 Rally with her friends in Civic Center Park in Denver on Friday, April 20, 2012.
Joe Amon, The Denver PostOfficers chase 20 year old Nathan Ryan as he makes a break for the closed the Norlin Quad on Colorado University Boulder campus to crackdown on pro-marijuana protesters on 4-20 at the school in Boulder, Colorado, Friday, April 20, 2012.
Joe Amon, The Denver PostColorado University Boulder closed the Norlin Quad on it's campus to crackdown on pro-marijuana protesters on 4/20 at the school in Boulder, Colorado, Friday, April 20, 2012.
Joe Amon, The Denver PostColorado University Senior Gabriel Kuettel is arrested trespassing on the Norlin Quad that is closed to crackdown on pro-marijuana protesters at the school in Boulder, Colorado, Friday, April 20, 2012.
Joe Amon, The Denver PostColorado University Boulder students and protesters get to the first line of defense at the closed the Norlin Quad on it's campus to crackdown on pro-marijuana protesters at the school in Boulder, Colorado, Friday, April 20, 2012.
Joe Amon, The Denver PostColorado University Boulder campus is closed to all but students. The Norlin Quad on the campus is closed to crackdown on pro-marijuana protesters at the school in Boulder, Colorado, Friday, April 20, 2012.
Joe Amon, The Denver PostProtesters against Colorado University Boulder closing the Norlin Quad on it's campus to crackdown on pro-marijuana protesters march up Broadway to the school in Boulder, Colorado, Friday, April 20, 2012.
Daniel Petty, The Denver PostA cloud of smoke rises up above the crowd at the annual 4/20 rally in Civic Center in downtown Denver on Friday, April 20, 2012. Hundreds turned out for the annual day celebrating marijuana.
Joe Amon, The Denver PostWaiting for 4:20 p.m. at the annual 4/20 Rally at Civic Center Park in downtown Denver April 20, 2013.
Hyoung Chang, The Denver PostAmy McBain of Evergreen, left, and Kim Logsdon of Denver celebrate 4/20 at Civic Center Park in Denver. A crowd of marijuana smokers gathered at the park to mark the counterculture holiday known as 4/20 on the first celebration since Colorado and Washington made pot legal for recreation use.
Joe Amon, The Denver PostJoshua Cevek of Colorado Springs smoking a huge pipe during the annual 420 Rally at Civic Center Park in downtown Denver April 20, 2013.
Joe Amon, The Denver PostThe annual 420 Rally at Civic Center Park in downtown Denver April 20, 2013.
Joe Amon, The Denver PostApril 20: The crowd runs away from the gun shots at Civic Center Park in Denver Colorado, Saturday April 20th, 2013 after the 4/20 pot rally. Two people were shot during Saturday's annual 4/20 marijuana rally, held on a day cannabis enthusiasts regard as a holiday called 4/20 that drew tens of thousands to Denver's Civic Center park. This is the first 4/20 marijuana rally since Colorado voters legalized marijuana use for people 21 and older in November. April 20, 2013 Denver.
Joe Amon, The Denver PostApril 20: Denver Paramedics, Denver Police officers and good samaritans at the scene attend to a shooting victim at Civic Center Park in Denver Colorado, Saturday April 20th, 2013 after the 4/20 pot rally. Two people were shot during Saturday's annual 4/20 marijuana rally, held on a day cannabis enthusiasts regard as a holiday called 4/20 that drew tens of thousands to Denver's Civic Center park. This is the first 4/20 marijuana rally since Colorado voters legalized marijuana use for people 21 and older in November. April 20, 2013 Denver.
Joe Amon, The Denver PostApril 20: The grounds are near empty at Civic Center Park in Denver Colorado, Saturday April 20th, 2013 after the 4/20 pot rally. Two people were shot during Saturday's annual 4/20 marijuana rally, held on a day cannabis enthusiasts regard as a holiday called 4/20 that drew tens of thousands to Denver's Civic Center park. This is the first 4/20 marijuana rally since Colorado voters legalized marijuana use for people 21 and older in November. April 20, 2013 Denver.
Helen H. Richardson, The Denver PostHundreds of people lit up joints, bongs, pipes and marijuana cigarettes at exactly 4:20 pm during the Colorado 420 Rally at Civic Center Park in Denver, Co on April 20, 2014. Thousands of people lit up and smoked marijuana to celebrate the now legal use of marijuana in the state of Colorado.
Joe Amon, The Denver PostThe smoke out at the 4/20 celebration at the Denver 4/20 Rally in Civic Center Park April 20, 2014.
Helen H. Richardson, The Denver PostA woman rolls a joint while wearing marijuana plant inspired socks and leggings while attending the Colorado 4/20 Rally at Civic Center Park in Denver on April 20, 2014. Thousands of people lit up marijuana pipes, cigarettes, joints, and bongs at exactly 4:20 p.m. to celebrate the now legal use of marijuana in the state of Colorado.
Cliff Grassmick, Daily CameraUniversity of Colorado police officers were out in full force to discourage any 4/20 activity. The University of Colorado shut down for 4/20 except for students and permit holders on Sunday, April 20, 2014.
Joe Amon, The Denver Post22-year-old Don Blosser of Denver (center) continues to celebrate after the smoke out at the 4/20 celebration at the Denver 4/20 Rally in Civic Center Park on April 20, 2014.
Brent Lewis, The Denver PostAttendees hold up a model while inside of a large inflatable ball during the Accomplice Clothing fashion show on Saturday, April 18, 2015 at Civic Center Park in Denver. The annual 4/20 Rally once again brought over a thousand smokers and music lovers to the park to celebrate the "holiday" which this year spans over the weekend. Musical acts this year included Too Short and Devin The Dude.
RJ Sangosti, The Denver PostA look-alike of Rapper and songwriter Wiz Khalifa is surrounded as he arrived at Civic Center Park in Denver, April 20, 2016. People gather at the park to celebrate the annual 420 day.
AAron Ontiveroz, The Denver PostStephanie Hodge smokes a gas mask marijuana smoking apparatus during Denver's annual 4/20 festival at Civic Center Park on Sunday, April 19, 2015. Thousands of people gathered to watch a free Rick Ross concert, while partaking in the day's goods and services.
John Leyba, The Denver PostA big crowd gathers at Civic Center and light up during 4/20 celebration April 20, 2016 in Denver, despite the official rally being cancelled due to weather.
John Leyba, The Denver PostJordan Mcintyre 18 years old of Denver takes a hit of her joint during 4/20. A big crowd gathered at Civic Center and light up during 420 celebration April 20, 2016 in Denver, despite the official rally being cancelled due to weather.
Kira Horvath, Special to The Denver PostJohn Henry dances during the Denver 4/20 Rally held Saturday, May 21, 2016 at Civic Center Park. The official rally was pushed back a month due to weather.
Kira Horvath, Special to The Denver PostBekah Christine, left, and Vanessa Lee smoke marijuana under their umbrella during the Denver 4/20 Rally held Saturday, May 21, 2016 at Civic Center Park. The official rally was pushed back a month due to weather.
Kira Horvath, Special to The Denver PostJames Jernigan swings his poi in front of the main stage during the Denver 4/20 Rally held Saturday, May 21, 2016 at Civic Center Park. The official rally was pushed back a month due to weather.
Joe Amon, The Denver Post
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A cloud of smoke covers the crowd at 4:20 p.m. at the Annual Denver 4/20 Rally in Civic Center Park, April 20, 2010.
ExpandBy Patrick Traylor | ptraylor@denverpost.com | The Denver Post
PUBLISHED: | UPDATED:
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Denver became Colorado’s epicenter for 4/20 events after the University of Colorado began shutting down its Boulder campus on that day in 2012. The Denver rally held in Civic Center Park has been highly structured in recent years, with monitored entrances, fences around the park and security guards. At the 2013 rally, two people were shot and another person grazed by a bullet.































