In 1987, a group of eight-year-old girls in California decided to plant a tree to help the environment. Then they decided to plant more trees and called their group the Tree Musketeers. As the group got older, they decided to find other children to continue their work. In 1997, they organized a campaign for 1 million children to plant 1 million trees around the country. They completed the task in four years. After this, each new group of Tree Musketeers helped the environment in different ways.