Balloon Airmail Day

Occurrence:
2X
Hashtags:
References:
wired.com/2010/08/0817us-airmail-balloon/
gone-ta-pott.com/Julycalendar.html
facebook.com/genesburgers/posts/1626161200985980

This event takes place twice annually, on the 17th of August and on the 1st of July.