Taken from Girl Scouts USA. More historical information can be found at that link.

Juliette "Daisy" Gordon Low assembled 18 girls from Savannah, Georgia, on March 12, 1912, for a local Girl Scout meeting. She believed that all girls should be given the opportunity to develop physically, mentally, and spiritually. With the goal of bringing girls out of isolated home environments and into community service and the open air, Girl Scouts hiked, played basketball, went on camping trips, learned how to tell time by the stars, and studied first aid.

Within a few years, Daisy's dream for a girl-centered organization was realized. Today, Girl Scouts of the USA has a membership of over 3.2 million girls and adults, a significant growth from its modest beginnings nearly a century ago. In fact, more than 59 million women in the U.S. today are Girl Scout alumnae. We invite you to learn about our robust organization and its rich history. From our willingness to tackle important societal issues, to our commitment to diversity and inclusiveness—Girl Scouts is dedicated to every girl, everywhere.