Pi Day is celebrated every year on March 14 because in the US when we express the date we put the month first, so today is 3-14. Pi Day was particularly exciting in 2015 because then the date was 3-14-15. It got even more exciting at 9H26 because – are you with me? 3.1415926 Not everyone swooned at the time, but I'm sure at least a few of you out there may have gotten at least a little quiver of excitement. To celebrate Pi Day today, here's an article and a video.