This year, the customary spring ritual falls on Monday, May 1, 2017.
Modern May Day celebrations have evolved into a hodgepodge of traditions including parties, sing-alongs, Old World maypole dancing, parades and workers' demonstrations, along with general protests on the streets of major capitals worldwide.
And just for a little contrast, in Hawaii it's ... Lei Day.
Historians generally agree that May Day celebrations probably originated in the spring fertility rites of ancient Rome, which occurred at about the same time of year marking celebrations honoring the goddess of spring, Flora.
By the Middle Ages, the day was being celebrated with a procession led by a "Queen of the May" chosen from a population of pretty teen girls, followed by the townspeople dancing around a maypole decorated with streamers and colorful spring flowers.