US

Once an underground phenomenon, pot holiday tries to go mainstream in Colorado

  • With the Colorado state capitol building visible in the background, partygoers dance and smoke pot on the first of two days at the annual 4/20 marijuana festival in Denver, Saturday April 19, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (AP Photo/Brennan Linsley)

    With the Colorado state capitol building visible in the background, partygoers dance and smoke pot on the first of two days at the annual 4/20 marijuana festival in Denver, Saturday April 19, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (AP Photo/Brennan Linsley)  (The Associated Press)

  • CORRECTS TO 4/20 MARIJUANA FESTIVAL -Police officers mounted on bikes patrol Civic Center Park on the first of two days at the 4/20 marijuana festival at Civic Center Park in Denver, Saturday April 19, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (AP Photo/Brennan Linsley)

    CORRECTS TO 4/20 MARIJUANA FESTIVAL -Police officers mounted on bikes patrol Civic Center Park on the first of two days at the 4/20 marijuana festival at Civic Center Park in Denver, Saturday April 19, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (AP Photo/Brennan Linsley)  (The Associated Press)

Denver police say they have issued 28 citations for public consumption of marijuana and arrested one person accused of attempting to distribute the drug so far this weekend as revelers celebrate the traditional pot holiday of April 20.

Public consumption of marijuana is still illegal in Colorado, the first state to legalize — and regulate — recreational marijuana.

Of the infractions police reported Sunday, 22, including the arrest, happened Saturday. The remaining citations were as of about 2 p.m. Sunday, hours before crowds plan to smoke pot at 4:20 p.m. MDT.

In Boulder, University of Colorado officials closed the campus to all but students, faculty and staff to ensure no 4/20 celebrations were held.

Denver is one of many cities across the country where 4/20 marijuana celebrations are planned Sunday.