There are couple reasons to that: Easter, 420 Denver Rally and The High Times Cannabis Cup.
While some people went to church and Sunday Easter dinner after that, others gathered into the Civic Center Park in Denver. Over ten thousand people came to celebrate the stoner holiday and send the collective smoke up in the air at 4:20pm. Hundreds of venders, musicians, artists and others participated in 420 Denver Rally past Sunday. On the other side of town, thousands of people attended High Times Cannabis Cup. It has been the biggest crowd ever at the Cannabis Cup.
If you didn't get a chance to be a part of this celebration, watch the video to stay updated: