Sources

• People - John Muir National Historic Site (US National Park Service)
• Environmental Preservation in the Progressive Era | DPLA
• Environmental Reform - an overview | ScienceDirect Topics
• The Conservation Legacy of Theodore Roosevelt | US Department of the Interior
• Progressive | Environmental history
• Progressive Environmentalism | US History II (American Yawp)
• Progressive Movement - water, effects, environmental, United States, chemicals, toxic, use, health
• National Monuments and the Antiquities Act
• National Park Service