From the OrigamiUSA website: Let’s get the world to fold! Celebrate origami by spreading the joy of paperfolding during World Origami Days, held each year from October 24–November 11, a 2-1/2 week celebration of the international community of origami. Help us make origami as visible as possible: teach a class, fold on the bus, give your friends origami, exhibit your models. The possibilities are limitless, just as with origami itself.
October 24 is the birthday of Lillian Oppenheimer (1898-1992), who founded the first origami group in America. She was also one of the founders of the British Origami Society and OrigamiUSA. A dynamic woman, she was delighted in the magic to be found in a piece of paper and wanted to share it with the world. November 11 is Origami Day in Japan where the paper crane has become a symbol of peace.
You can read Lillian’s obituary from the New York Times here.