Rachel Carson's Silent Spring is usually considered the progenitor, or the first instance of, the environmental movement. Prior to the publication of this work, there were some famous individuals who advocated for environmental conservatism (most notably former president Theodore Roosevelt) but this particular book acted as a wake-up call for American society. It had previously given very little thought to its impact on the natural world.
Carson laid out the problem with pesticides, especially DDT, and then transitioned to show how simple types of human behaviors could have negative effects on the ecosystem. At the time, not many Americans may have realized how their lifestyle affected wildlife or the natural world. Her work was the first "green" book to be a bestseller.
Following this, a number of major changes galvanized American society. The first Earth Day was put into law by former president Richard Nixon. The Environmental Protection Agency was founded in 1970 as a way of conserving resources and managing the ecosystem. Recycling became mainstream at about the same time.
Today, many environmental concerns, like deforestation and global warming, are taught in schools so that children understand how their life affects the natural world. Many major milestones have been reached as a result of Carson's groundbreaking work, although we still contribute to many negative effects on our environment.