Zach was a 17-year-old from Minnesota who was diagnosed with a terminal form of bone cancer at 14. As he ran out of any possible treatments to battle the cancer, he wrote "Clouds" as a goodbye for friends and family.
So on Friday, Minnesota decided to say goodbye to Zach.
Organized by local radio station KS95, people touched by Zach's story gathered just south of Minneapolis and filled up the Mall Of America.
Zach passed away in May, and since then his song has reached over 8 million views on YouTube and hit number one on iTunes.
Originally, the radio station put out a call for 1,000 choir members, but that number swelled by nearly fivefold.
From the looks of it, Zach's parents seemed pretty happy about being able to give their son a proper send-off.
