History: New York City, 1980s, United States

Mass transit use in New York City is the highest in the United States, and gasoline consumption in the city is the same rate as the national average in the 1920s. The city's high level of mass transit use saved 1.8 billion gallons of oil in 2006; New York City saves half of all the oil saved by transit nationwide. The city's population density, low automobile use and high transit utility make it among the most energy efficient cities in the United States. Its greenhouse gas emissions are 7.1 metric tons per person compared with the national average of 24.5. New Yorkers are collectively responsible for 1% of the nation's greenhouse gas emissions though they comprise 2.7% of the nation's population. The average New Yorker consumes less than half the electricity used by a resident of San Francisco and nearly one-quarter the electricity consumed by a resident of Dallas.
In recent years, the city has focused on reducing its environmental impact. Large amounts of concentrated pollution in New York has led to a high incidence of asthma and other respiratory conditions among the city's residents. The city government is required to purchase only the most energy-efficient equipment for use in city offices and public housing. New York has the largest clean air diesel-hybrid and compressed natural gas bus fleet in the country, and also, by mid 2010 the city has 3,715 hybrid taxis and other clean diesel vehicles, representing around 28% of New York's taxi fleet in service, the most in any city in North America.
The city government was a petitioner in the landmark Massachusetts v. Environmental Protection Agency Supreme Court case forcing the EPA to regulate greenhouse gases as pollutants. The city is also a leader in the construction of energy-efficient green office buildings, including the Hearst Tower among others.
The city is supplied with drinking water by the protected Catskill Mountains watershed. As a result of the watershed's integrity and undisturbed natural water filtration system, New York is one of only four major cities in the United States with drinking water pure enough not to require purification by water treatment plants.