On Sunday people in Denver, Colorado celebrated the historic first 4/20 since recreational sales started in the state. Tens of thousands of people, many from all over the country, took part in events in the city celebrating pot.

Even with so many people consuming marijuana together there were relatively few emergency health issues. According to Denver Health Medical Center, paramedics took only 18 individuals from 4/20 events to area hospitals for any reason, and of this group four were taken to detox. This number was partially attributable to the fact that yesterday was a sunny unseasonably warm day, making dehydration a threat.

I was interested to see how these number stack up against the result of holidays that tend to revolve around alcohol consumption, such as St. Patrick’s Day, but when I asked the Denver health center said they didn’t specifically track that number last month.

So instead I decided Boston would be a good point of comparison. It has almost the exact same population as Denver and Boston is known for its St. Patrick’s Day celebration in the same way Denver is known for 4/20.

In 2012, Boston’s alcohol related emergency visits for St. Patrick’s Day weekend were roughly double what they were for a normal weekend. It would seem St. Patrick’s Day was mainly responsible for around 60 additional ER visits for just alcohol related issues in Boston that weekend.

Given that ten of thousands of people can gather to use a substance and the result is very few issues, the question naturally becomes is it worth spending so much money to keep it illegal in the other 48 states?

This year I published my book After Legalization: Understanding the future of marijuana policy. To celebrate 4/20 the ebook version is on sale for $1.99 until the end of Monday.