Skip to main content

A Slice of Pi (π) Day History

A Slice of Pi (π) Day History
How a gathering at San Francisco’s Exploratorium became a national holiday
Prince of Pi

Prince of π

March 14 is Pi (π) Day, the annual celebration of a never-ending number—and Albert Einstein’s birthday. How did pi inspire a national holiday and an international celebration thousands of years after its discovery? It all started at the Exploratorium with former staff physicist, tinkerer, and media specialist Larry Shaw.

In 1988, three years after the death of Exploratorium Founder Frank Oppenheimer, staff gathered at a retreat in Monterey, California, to soul search and brainstorm. It was there that Shaw linked March 14 (3.14) with the digits of pi (3.14159…), seeing it as an extraordinary opportunity to bring Exploratorium staff together. And π Day was born. 

On the first π Day, at 1:59—the π numbers that follow 3.14—Larry and his wife, Catherine, set up a table on the museum's floor topped with fruit pies and a tea urn for the celebration.

A few years later, Larry's daughter, Sara, discovered that π Day was also Einstein's birthday (b. 1879) so a celebration of his life was added to the π Day festivities. 

Larry created and installed the "Pi Shrine," a circular brass plaque, in the center of a circular classroom constructed of circular cinderblocks. He led a winding parade around the museum with his boombox blaring the digits of π to the music of "Pomp and Circumstance." The parade ending by circumnavigating the Pi Shrine 3.14 times while singing "Happy Birthday" to Albert Einstein.

π Day became an annual Exploratorium tradition for staff and the public, and the idea snowballed into something much bigger. Now it’s celebrated by math lovers and educators worldwide. In March 2009, π Day became an official U.S. national holiday.

Until his passing in 2017, Shaw, affectionately known as the Prince of π, led π Day parades yearly at the Exploratorium. Today, the Exploratorium continues the tradition by hosting an annual π Day, a public celebration that features a π-themed activities, antics, rituals, and—and, of course, plenty of pie.

Be sure to share your π Day spirit with us at #PiDaySF and @Exploratorium.