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Philadelphia committee led by Benjamin Franklin attempts to regulate waste disposal and water pollution.
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Henry David Thoreau publishes Walden
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President Abraham Lincoln issues the Emancipation Proclamation, declaring that all enslaved people in Confederate-held territory are to be set free.
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The Thirteenth Amendment to the United States Constitution is ratified, officially abolishing slavery in the United States
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The term ecology is coined in German as Oekologie by Ernst Heinrich Philipp August Haeckel
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The Fourteenth Amendment to the United States Constitution is ratified, granting citizenship to all persons born or naturalized in the United States, including former slaves.
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The term acid rain is coined by Robert Angus Smith in the book Air and Rain
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The Fifteenth Amendment to the United States Constitution is ratified, prohibiting the denial of the right to vote based on race, color, or previous condition of servitude.
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The Supreme Court's decision in Plessy v. Ferguson upholds the constitutionality of racial segregation under the "separate but equal" doctrine.
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The term smog is coined by Henry Antoine Des Voeux in a London meeting to express concern over air pollution
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US Congress created the National Park Service
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The Supreme Court's decision in Brown v. Board of Education declares state laws establishing separate public schools for black and white students to be unconstitutional, overturning the "separate but equal" doctrine established in Plessy v. Ferguson.
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The Montgomery Bus Boycott begins in response to the arrest of Rosa Parks for refusing to give up her seat to a white passenger on a bus in Montgomery, Alabama. The boycott lasts for 381 days and leads to the desegregation of the city's bus system.
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Rachel Carson publishes Silent Spring
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The March on Washington for Jobs and Freedom takes place, where Dr. Martin Luther King Jr. delivers his famous "I Have a Dream" speech advocating for civil and economic rights for African Americans.
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President Lyndon B. Johnson signs the Civil Rights Act of 1964 into law, prohibiting discrimination based on race, color, religion, sex, or national origin, and ending segregation in public places.
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President Lyndon B. Johnson signs the Voting Rights Act of 1965 into law, which prohibits racial discrimination in voting, aiming to overcome legal barriers at the state and local levels that prevented African Americans from exercising their right to vote as guaranteed under the Fifteenth Amendment.
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The Apollo 8 picture of Earthrise
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First Earth Day – April 22. Millions of people gather in the United States for the first Earth Day. US Environmental Protection Agency established
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Montreal Protocol on substances that deplete the ozone layer entered into force
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The Kyoto Protocol was negotiated in Kyoto, Japan in December. Countries commit to reduce their emissions of carbon dioxide
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U.S. rejects the Kyoto Protocol
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U.S. announces it will cease participation in the Paris Agreement on climate change mitigation
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U.S. announces it will rejoin the Paris Agreement on climate change mitigation