May Day! May Day!
In most nations of the world May Day is celebrated as International Workers' Day or Labour Day. Only two countries do not:
In the United States and Canada, Labor (or Labour) Day is celebrated on the first Monday in September, so as to not be associated with all those REDS on May 1.
Of course, celebrations of May Day date back long before labor movements. Exactly one half year since November 1 means the end of winter weather (for the northern hemisphere) and serves as a call for celebration. Perhaps a romp around the Maypole.
May I make my fond excuses for the lateness of the hour,
but we accept your invitation, and we bring you Beltane's flower.
For the May Day is the great day, sung along the old straight track.
And those who ancient lines did lay will heed the song that calls them back.
In the Society for Creative Anacronism, May 1 is the first day of the new year. Reckoning from the founding of the Society in 1967 C.E., today is the first day of Anno Societatis (A.S.) XLV (45).
"May Day! May Day!" is an internationally recognized distress signal (from the French from the French venez m'aider, meaning "come (and) help me").
HT to Rudolf for the map.