Scientific, not Political
If you've ever seen the Statue of Liberty, you may have wondered why the statue is green. The statue was a gift from the French in 1886, commemorating the century that passed since the American revolution. (The statue was supposed to be complete by America's centennial, 1876, but it fell behind schedule.)
The French didn't paint the statue green for any symbolic reason. No, the reason for the color is actually more scientific than political.
The Statue of Liberty is green for the same reason your car is slowly turning brown. Rust is a chemical reaction between the iron in the car and the oxygen in the air. This sort of reaction between oxygen and certain metals is known as oxidization.
Copper experiences a similar reaction with oxygen and water over time. Leave a penny outside for long enough and it will turn green---this is the copper reacting with water and oxygen in the atmosphere around it. Unlike rust, however, the green chemicals that form around copper left outside do not eat away at the penny. They actually protect it from the elements around it.
The Statue of Liberty is made of copper, so this oxidization is the reason for the statue's famous color.